Can the Same Causal Factor Be Both a Necessary and a Sufficient

Multiple Choice

Can the same causal factor be both a necessary and a sufficient condition of the effect?

A) Yes, because all sufficient conditions are also necessary conditions.
B) Yes, because some conditions are both necessary and sufficient.
C) Yes, because all necessary conditions are also sufficient conditions.
D) No, because by definition, sufficient conditions are unnecessary.
E) No, because by definition, necessary conditions are insufficient.