Can we draw the following hypothesis from the context (see options)? 

Context:

It has become increasingly clear that Iran is making rapid progress toward attaining a nuclear weapons capability as U.S. officials have confirmed the presence of various nuclear sites that Tehran has failed to disclose

Hypothesis: Tehran was not forthcoming about something.
Available choices:
[a]. Yes.
[b]. It's impossible to say.
[c]. No.
[a].