I'll take B. It's closest to the argument.

If radioactive material --> genetic mutation (It x --> y)
then radioactive material --> birth defect (x --> z)
but not logical, because z is caused by some othe characteristic of x (genetic mutation)

DELETED

My take on this question is a bit different. Here goes.

The statement describes that there's a one to one correspondence between cause and effect; one effect can be caused by one cause only. Thus this holds good:

cause --> effect 1

but not this:

|----> effect 1
cause --|
|----> effect 2

Now coming to options:
(A) Talks about two effects - "donation of 1000 dollars" and "volunteering at the children's hospital". No cause is discussed. We can safely ignore it.
(B) One cause "radioactivity" had the effect "genetic mutation". Then one cause "genetic mutation" had the effect "birth defect". So far so good - in line with the flawed reasoning provided in the basic statement. However, now it says "genetic mutation" caused "birth defect". This "chained cause-effect relationship" is not described in the statement, so doesn't fit well.
(C) Cause -> effect is "complex structure" -> immense power. Its right as far as the statement goes, but it has not made any flawed logical conclusions - so we can let it go too.
(D) Same single cause-effect relationship described. Nowhere it describes the assertion that one cause should have one effect or vice versa. This also doesn't fit well.
(E) "Heating" (cause) leads to "evaporation" (effect). Then comes the assertion that thus, heating causes evaporation (only one effect - evaporation - attributed to one cause - heating). Of course this is flawed, because there's another effect - water/liquid getting hot. This is a flawed reasoning.

Thus I'd go with E.

Those who think the option would have been B, might be correct in reasoning that the single cause "radioactivity" is attributed to the effect "birth defect" (while in reality the birth defect may be caused by anything else as well - say chemicals). This is true. However the assertion uses a "cause chaining" in which the cause's (genetic mutation's) cause (radioactivity) is attributed to the effect (birth defect). This is not clearly described in the statement.

Anyone with a different reasoning?

Can you please post the OA Vithal?
_________________

Who says elephants can't dance?

A is the OA.. Can some one provide explaination as to why A is right?

Will go with A.

Now from the statement
Cause --> effect1
Effect2
Wrong Inference that
cause --> effect2

Now in A
Donor(cause) --> donation of $1000(effect1)
Effect2 = volunterring at children's hospital

Wrong inference
Donor(cause) --> volunterring at children's hospital(effect2)