1. Phineas T. Barnum C. was born in Bethel, Connecticut, on July 5, 1810. - you have to choose C because it is the only singular verb; if the subject was plural, then any of the remaining options would be correct.
2. D. Do you have all the necessary materials for the project?
3. The early professional efforts of P.T. Barnum A. weren't very successful.