I don't think it is fair that Watson and Crick were credited with the discovery when so many other scientists were involved because all other scientists also contributed in the work and work harder for it so the credit must be given to all scientists. If the credit will not given to other scientists so it is an unfair act so my opinion is against the credit given to Watson and Crick.
"Mechanical" would be the kind of reproductive isolation among the choices given in the question that has been observed in these two species. The correct option among all the options that are given in the question is the first option or option "A". I hope that the answer has come to your help.