A sociologist recently studied the correlation between

Paraphrase: 20% of the no. interviewed were doing psychology and their parents read it, so bingo, psychologists can influence their children more.

However, what if 30% of the no. interviewed study economics and their parents did?

So, i expect a comparison with other possible disciplines whose students were interviewed.

a)The percentage of those interviewd whose intended career was the one they actually pursued
Out of scope.

b)The percentage of those interviewed whose parents were not psychologists
Irrelevant

c)The percentage of those interviewed who were pursuing the career of their parents
My choice

d)The percentage of those interviewed who were planning to become psychologists
Irrelevant

eThe percentage of those interviewed who were undecided about their future careers.
Irrelevant

It's (C) for me.

C for me for the above reasoning

Bumping :
Its C for me too.
Please contribute so that we can find the right answer.
Thank you.

I guess answer is B

The argument states that 20% OF THOSE WHOSE PARENTS ARE PSYCHOLOGISTS chose careers in psychology

But what if only 30% OF THOSE WHOSE PARENTS ARE DOCTORS OR ENGINEERS chose that field

Then engineers or doctors will have more influence then psychologists

Option B makes sense

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Option C as we need to know what % of students are opting their parents career.

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Reading your reasoning, I think you may misread the option (B).

b)The percentage of those interviewed whose parents were not psychologists

In such a statistics-related question, I think a mathematical example might help you a lot in understanding properly.

Let's say, we survey 100 young adults in total.
Just imagine 40% have psychologists parents, so the number of these children is: A=40% x 100 = 40
Just call a the number of those whose parents were psychologists were pursuing careers in psychology themselves. From premise, a/A = 20%

Similarly, we will call B, C, D... and b, c, d... the number of ones whose parents are not psychologists (doctors, engineers, etc.) and number of ones pursuing their parents' career (doctors, engineers, etc.), respectively.

Considering the percentage a/A only, author concludes that "psychologists have more influence on their children's career choice than do members of other professions". He must have assumed that there is no any b/B, c/C, or d/D, etc. that is larger than 20%.

Option (B) simply provides information about B, C and D, whereas what we actually need is b/B, c/C, or d/D. In other words, (B) doesn't help. OUT.

Option (C) talks about b/B, c/C, d/D hence is exactly what we need to evaluate the conclusion.