Answer
A → p; B → r
Explanation:
We know [x] ∈ I, ∀ x ∈ R. Therefore,
sin(pi[x]) = 0, ∀ x ∈ R. By theory we know that sin (pi[x]) is differentiable everywhere, therefore (A) ↔ (p).
Again, f(x) = sin{pi(x - [x])}
Now, x - [x] = {x} then pi(x - [x]) = pi{x}
Which is not differentiable at x ∈ I.
Therefore, (B) ↔ (r ) is the answer.