Which one of the following conditions on a group g implies that g is abelian? (a) the order of g is p for some primep (b) every proper subgroup of g is cyclic (

Which one of the following conditions on a group G implies that G is abelian? (A) The order of G is p for some primep (B) Every proper subgroup of G is cyclic (C)Every subgroup of G is normal in G D)The function f:G-G, defined by f)=x for all xe G, is a homomorphism