Forgive me if I am wrong, but I truly believe the answer to this question to be "D."
The stimulus is asking:
Is the standard deviation of T positive?
Well,... stem question #1 clearly states that all elements of set T are positive. Thus, it is given that the ultimate standard deviation of set T is, in fact, positive.
Am I wrong?
1. Positive (+ve) elements (of the set) come in at least two flavors: (1, 1, 1, 1, 1, 1) or (2, 4, 5, 66, 77, 100).
In first case, SD is 0 where as in second case, SD is +ve. NSF.
2. Range is zero means, the elements of the set are same irrespective of signs. So SD is always 0. SUFF.