Mr. Smith is very interested in our plan. I spoke to him on the phone last night.

A. Mr. Smith, who is very interested in our plan, I spoke to on the phone last night.

B. Mr. Smith, to whom I spoke on the phone last night, is very interested in our plan.

C. Mr. Smith is very interested in our plan to whom I spoke on the phone last night.

D. Mr. Smith, who I spoke on the phone last night, is very interested in our plan.