<h2><u>Answer</u> :</h2>
The correct option is A. If a dominant allele is present, the recessive allele won’t be seen.
The dominant allele is the one which appear, and the recessive one isn't shown.
For example - If a person has 2 alleles of eye colour as B ( black ) and b ( brown ), in which black is dominant and the brown one is recessive, then the person will have black eye colour because only dominant allele shows its characteristics.
_____________________________

More growth of flowers and or more plant food/water supply for it
I would say D and A are your answers :)
I believe you meant to say is this mistake called a base pair and if that is your question then no. it would be called Mutation. But you can double check that answer.