Add who (that) or which (that) to these sentences, but only where neccessary:

Add who (that) or which (that) to these sentences, but only where neccessary:
a. Is that the woman / you told me about?
E.g: Is that the woman you told me about?
b. Is that the girl / wrote to you?
c. The car / my brother bought wasn't expensive.
d.Alex was the man / you met last week