Answer:
d. in an increased quantity of the normal gene product
Explanation:
Gain of function mutation is the mutation in which the gene product acquires a new function , resulting in increased quantity of normal gene product.
it is of 2 types :
1) Hypermorphic .
2) Neomorphic.
Hypermorphic :
Excessive expression of the gene product leads to excessive gene action.The mutant phenotype may be more severe or lethal in the homozygous genotype than in the heterozygous genotype.
Neomorphic :
The mutant allele has novel function that produces a mutant phenotype in homozygous and heterozygous organisms and may be more severe in homozygous organisms.
Hence option D is the right answer.
