<span>If Billy believes evolution is slow and continuous, then he also believes in gradualism. Gradualism refers to the type of evolution that takes a long time to occur - as the name itself say, it all happens gradually, one segment at a time. This process is very slow, and cannot happen overnight, which is something Billy understands well.</span>
20 years would be my answer
I think it's between A and B...
i havent done this in a while sorry i cant be of more help :(