Each of the species of a certain type of insect has at least one of

The passage says.
=> 1st study implies,
Any species with Trait A will have At least one of the trait B and C
That means If any insect have A he will have either B or C or Both
A = B/C or B + C -------(1)

=> 2nd study implies,
Any species with Trait C will have At least one of the trait D and E
That means If any insect have C he will have either D or E or Both
C = D/E or D + E -------(2)

=> 3rd study implies,
Any species with Trait B will have C as trait
That means If any insect have A he will have trait C in him in addition
B = B + C -------(3)

Now, for ex.
If an insect have Trait A
Other following traits will be.
=>>> A+B+C+D/E ------(4) (because A has to have atleast B/C with it and B will surely have C, also C will have either of Trait D/E)

Also, the other traits that could be followed are,
A+C+D/E ----(5) (since a can have any of the B and C and C follows Any of the D and E)

If you followed all three equations in other traits combinations you will see A and C are must together

From above we can determine that Trait A will have Trait C for sure.

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Given:
Trait A = B or C
Trait C= D or E
Trait B has Trait C

Analysis:
If A then B then must C then should have D or E
or
If A then C then D or E

If B then C then D or E


Result: In above cases,
If B then C must be present ( given in question. In addition to this relation)
if A then C must be present.

But why not A to B? It is not certain that A will lead to B. Why are not both options valid: A to B and A to C?

­From the passage we know that
1. if A is present then at least one of B and C are also present. So the possible combinations are -
a. if A then B
b. if A then C 
c. if A then (B and C)

2. And if B is present then C is present. So, if B then C

Combining these two statements, we can see from statement 1,
a. if A then B, and if B then C so, if A then C
b. if A then C - we can't infer anything more because if B then C is not the same as if C then B.
c. if A then (B and C). The intersection of B and C will be the same as B (from statement 2), and since if B then C. So we get the same as (a), if A then C again.

So, looking at the possible combinations, we can only infer that if A then C is MUST BE TRUE. But if A then B is COULD BE TRUE (true in case a. and case c. but FALSE in case b.) and we can't conclude that relation with the given data.

Hope this helps­

Thanks, yes it does. The focus should lie on the difference what is explicitly stated and what is implied. Study 1 explicitly states that if A then B or C, leaving out the possibility that A must lead to C, as such information is not yet provided. Only through study 3 that explicitly mentions that B leads to C, we now know for certain, that if A then there must be C, but not B. Only if A leads to B, then all three will be present. But A can also go directly to C, leaving B out. And as there is no study provided that would show that C leads to B, the only thing that we can infer with 100% certainty is that A will lead to C. 

I have to work on that, what is the cause, what the effect and what it is not. But thanks again. 

why can't it be B & C? since that is there in the options itself and the statement 3 says that as well.­

Because ideally it said additional to B & C, so I thought it has to be options other than B & C in it and now seeing the answer I realise it has to be a different combination - can someone please explain the grammar part of it?

­It says "B and C" already and asks to "imply", thus, the direct rewrite B to C is not as good as implying A to C.

1) A-> B/C
2) C->D/E
3)B->C

Implies:
A->B->C->D/E
or
A->C-D/E

Hence A will always lead to C

(A,C) is ans

We are able to form the below cases
AC
ABC
CD
CE
CDE

Cant we say that whereever E trait is present, C trait is also present? Please tell me why is this ans choice incorrect?
GMATNinja MartyMurray karishma @E-GMAT­

­It says whereever C is there, at least one of D and E is there. This does not mean the opposite, that is whereever E is there C will be there.

The possible options would be many more, few are added below

• AC
• ABC
• CD
• CE
• CDE
• D
• E
• ABCD
• ABCE
• ABCDE
• BCD
• BCDE
• BCDE
• ACD
• ACDE
• ACE
• DE

So, in the combinations E and DE, C is not present.

­Each of the species of a certain type of insect has at least one of five significant traits: A, B, C, D, and E. Furthermore, one study has determined that any species with Trait A has at least one of the Traits B and C. Another study has determined that any species with Trait C has at least one of the Traits D and E. And a third study has determined that any of the species with Trait B has Trait C. The results of each study are correct.

In addition to the relationship between Traits B and C that is stated explicitly with respect to the third study, the passage implies that any of the insects that has Trait ____X____ also has Trait ____Y____.

Select different options for X and for Y such that the following statement most accurately describes the passage. Make only two selections, one in each column.­

Reading the statement with the blanks, we see that, for X and Y, we have to find traits such that, if an insect has the first, the X trait, the insect must also have the second, the Y trait.

Also, the relationship that the completed statement describes must be "in addition to the relationship between Traits B and C." So, the correct answers won't be B and C.

We can start to determine which traits fill the blanks by listing what the passage says in short form:

A --> B or C

C --> D or E

B --> C

Considering the first statement, A --> B or C, we see that that information does not allow us to answer the question because it indicates that an insect that has A could have B or C and thus doesn't indicate that an insect that has A must have one of the two traits B and C.

Also, it doesn't indicate that an insect that has B or C must have A. In fact, for all we know from the first statement, an insect with B or C may not have any of the other traits listed. After all, the first statement does not say that an insect that has B or C must have any other trait.

The second statement also does not allow us to answer the question because it indicates that an insect that has C could have D or E and thus doesn't indicate that an insect that has trait C must have one of the two traits D or E.

Also, it doesn't indicate that an insect that has D or E must have C. In fact, for all we know from the second statement, an insect with D or E may not have any of the other traits listed. After all, the second statement does not say that an insect that has D or E must have any other trait.

The final statement, B --> C is interesting. If we combine it with the first statement, we see the following.

From the first statement, we know A --> B or C.

Combining that information with B --> C, we get the following.

A could be associated with B, in which case, since B --> C, then A is also associated with C. In other words, A --> B ALWAYS means A --> B --> C.

Alternatively, A could be associated with C alone, as in A --> C.

In either case, A --> C.

So, we see that the following is true:

the passage implies that any of the insects that has Trait ____A____ also has Trait ____C____.

Correct answer: A, C­