单项选择题

A.∀x(O(x)→∀y(P(y)→¬D(x)))
B.∀x(O(x)→∃y(P(y)∧¬D(x)))
C.∃x(O(x)∧∃y(P(y)∧¬D(x)))
D.∃x(O(x)→∀y(P(y)→¬D(x)))