Kobayashi coffee has more caffeine than Marlowe Select coffee. But

E is the only choice when introduced as additional premise will invalidate the conclusion - it follows that Kobayashi coffee has more caffeine than Valentino coffee

Kobayashi coffee has more caffeine than Marlowe Select coffee. But since Chula Vista coffee has more caffeine than Valentino coffee, it follows that Kobayashi coffee has more caffeine than Valentino coffee.
Any of the following, if introduced into the argument as an additional premise, makes the argument above logically correct EXCEPT?
(A) Marlowe Street coffee has more caffeine than Valentino coffee.
(B) Marlowe Street corree has more caffeine than Chula Vista coffee.
(C) Marlowe Street and Chula Vista coffees have the same amount of caffeine.
(D) Kobayashi and Chula Vista coffees have the same amount of caffeine.
(E) Chula Vista coffee has more caffeine than Kobayashi coffee.

% of Caffeine in Kobayashi coffee= K
% of Caffeine in Marlowe Select coffee = M
% of Caffeine in Chula Vista coffee = C
% of Caffeine in Valentino coffee = V
Premise 1 - K > M
Premise 2 - C > V
Conclusion - K > V
Option A - M > V - Concurs with the conclusion
Option B - M > C - Concurs with the conclusion
Option C - M = C - Concurs with the conclusion
Option D - K = C - Concurs with the conclusion
Option E - C > K - Does not Concurs with the conclusion because if C >K, then we can not be sure whether K>V because two cases are possible
C > V > K
C > K > V

Thus E is the correct answer.

Only E stands here....
given K>M
C>V
so K>V
look for option that says
M=C
M>V
K>C

Consider kudos if my post helps!!

Archit

Am i the only one who thinks D is right ?

Nightmare007
Even I had picked D, but on careful observation I realized its not the correct answer,
We are given that K>M, C>V, now substitute K = C in C>V, we get K>V,
So D is incorrect.

E says - Chula Vista coffee has more caffeine than Kobayashi coffee.
i.e C>K
But we know K>M and C>V, now if C>K, we cannot conclude that K>V.
Hope this helped.

1. K>M
2. C>V

Conclusion: K>V

We have been asked to find the only option that would WEAKEN this conclusion


(A) Marlowe Street coffee has more caffeine than Valentino coffee. - In other words, M>V. Since K>M, we can conclude that K>V. This strengthens the conclusion, not weakens it. Hence, eliminate (A)

(B) Marlowe Street corree has more caffeine than Chula Vista coffee. - In other words, M>C. This means than K>M>C>V. So, K>V; this strengthens the argument, not weakens it. Hence, eliminate (B)

(C) Marlowe Street and Chula Vista coffees have the same amount of caffeine. - In other words, M=C. this means that K>M=C>V. So, K>V. This strengthens the conclusion and not weaken it. Hence, eliminate (C)

(D) Kobayashi and Chula Vista coffees have the same amount of caffeine. - In other words, K = C. this means that K=C>V. So, K>V. This strengthens the conclusion and not weaken it. Hence, eliminate (D)

(E) Chula Vista coffee has more caffeine than Kobayashi coffee. - In other words, C>K. And C>V. Now, we cannot definitely establish that K>V. Hence, (E) weakens the certainty of this conclusion. So, (E) is the right answer.