the answer is A because restriction enzymes function in cutting strand of DNA at specufic sites
C55H72O5N4Mg boooooooooooom
When the fish is put into fresh water, suddenly the concentration around them is very low and the water potential is extremely high. Water will now move from the relatively high water potential in the water to the relatively low water potential in the cells, the cells start to burst and the fish dies.
I'm not 100% sure, but I'd say the availability of vaccines and medicine.
Explanation: The allele for black is B and the allele for white is W. The heterozygous phenotype is known as erminette.
