Given the task definition and input, reply with output. In this task, you will be presented with a text, a pronoun from the text, and two candidate names. You should determine what the pronoun refers to and classify the answers into A, B, or Neither. A and B here are referring to option A and option B. Position of the pronoun in the text is showed within two "_"s.

After teaching mathematics and physics in Ghana with the Peace Corps (1963-1965), Gibbard studied philosophy at Harvard University, participating in the seminar on social and political philosophy with John Rawls, Kenneth J. Arrow, Amartya K. Sen, and Robert Nozick. In 1971 Gibbard earned his Ph.D., writing a dissertation under the direction of John Rawls. Soon after _his_ doctoral degree, Gibbard provided a first proof of a conjecture that strategic voting was an intrinsic feature of non-dictatorial voting systems with at least three choices, a conjecture of Michael Dummett and Robin Farquharson. <sep>, Pronoun: his <sep>, A: Gibbard <sep>, B: Michael Dummett
A