(EEAR 2016/2017 ) - QUESTÃO

Choose the alternative that contains the right use of the relative pronoun, in order to write the two sentences below as a single sentence: 

That is the teacher. I spoke to her about my grades.

a) That is the teacher to whom I spoke to about my grades.
b) That is the teacher to who I spoke to about my grades.
c) That is the teacher to whom I spoke about my grades.
d) That is the teacher who I spoke about my grades.

A preposição to exige como pronome relativo whom.