True meaning of restrictive relative pronoun

Hello...

This is in relation to

As I think I didn't present clearly there, I present again.
I am sorry for the inconveniences that I caused, but as I was unclear about what was it that I was asking, I couldn't ask questions clearly.

A: She had two sons who were studying law at university and a daughter who was still at high school.

The A above, does it mean...

B: She had only two sons and one daughter.

C: She had more than two sons and more than one daughter.

D: We cannot be sure. We can be sure only that she had at least two sons and one daughter.

Among B, C and D, which should be native speaker's sense of English here?

There are no commas before who.