(Q) : Is A a friend of C ?
(S1) : A is a friend of B.
(S2) : B is a friend of C

A

if (S1) alone answers (Q)

B

if (S2) alone answers (Q)

C

if (S1) and (S2) together answer the question (Q), but neither of these alone can answer

D

if (S1) and (S2) are not sufficient to answer the question (Q)