For the purposes of this problem (and most other purposes) if you have a question that divides answers in 47%:A 51%:B 2%:'stupid_question_doesn't_fit_me_I'll_answer_randomly', then it's still perfectly okay.
No, answering randomly is not okay. You will not be able to reproduce the bit string if there is a random answer any more than two source texts with a single bit changed between them will produce the same hash.