Among the following propositions two are related in such a way that they cannot both be true but can both be false.
Select the code that states those two propositions.
Propositions: (a) Every student is attentive. (b) Some students are attentive (c) Students are never attentive (d) Some students are not attentive
(A) (a) and (b)
(B) (a) and (c)
(C) (b) and (c)
(D) (c) and (d)