Please provide an explanation

The easiest way to approach this question is process of elimination. We see B mentioned around line 27. C is mentioned around line 43. Around line 48, we see mentioned E, noting that a parent may lose career potential by needed to be around their children. Several lines around 55-60 mention D, career specialization. A may be true in real life, but isn't mentioned by the passage. For EXCEPT questions where you're finding 4 things that were mentioned in the passage and one that was not, it's usually easiest to knock of those you know you saw and then quickly glance over it again to knock off the remaining couple, leaving you with the right answer.

Can you clarify? I do not understand why it is A over D. The passage talks about how nonprofessional jobs are more flexible.

The passage never compares professional and nonprofessional jobs directly, while it does specifically talk about specialization. So when it talks about lawyers, the article mentions that women with children tend toward working in trusts and estates rather than in litigation. However, the article does not say that female lawyers with children seek out nonprofessional jobs to achieve greater flexibility as (A) would suggest. Further, the article talks about "nonprofessional women" focusing on a particular subset of jobs within the nonprofessional market that provides more flexibility but does not say that they were seeking jobs as secretaries rather than as lawyers or teachers. Does that make sense?

But the passage does say that women have to be teachers instead of principles. How would this not be considered professional vs. non professional?

When the passage refers to nonprofessional careers in the final paragraph it specifically calls out secretarial work and jobs in department sales. The passage does not infer that being a teacher is a nonprofessional job while being a principle is a professional career.

I'm glad I wasn't the only person that was stuck on this one. I picked A over D, simply by luck. Even after reading the aforementioned explanations, I still don't understand why A is correct.