Answer:
A. single-gene
Explanation:
It is controlled by a single gene that has two alleles. The allele for a widow's peak is dominant over the allele for a hairline with no peak.
I think the answer is B. Immigration must outpace emigration. Hope this helps!
The greatest threats to coral reefs is the rising temperature of the oceans as a result of climate change and the acidification of the oceans due to increased levels of carbon dioxide in the atmosphere which dissolves in the ocean and forms carbonic acid.Aug 3, 2015
