As you see on the table, there are 3 ways the offspring can get the dominant trait. RR, Rr, and rR (order was switched for clarification). There are 4 total outcomes. In this case, the problem can just be treated as a probability question.
3 out of 4, or 3/4 * 50 is 37.5, which can be rounded to D. 38.
The answer to your question is ( Blastocyst formation) takes place last.
This is a theory because this has been proven by scientists years ago. The evidences to prove this theory were shown.
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