A condition, where a certain gene is present in only a single copy in a diploid cell is called:
Hemizygous
The correct option is D:
Explanation of the correct option:
Explanation of the incorrect options:
Option A:
Heterozygous is the condition of having both dissimilar alleles or different alleles.
Option B:
The relationship of spending complete life with a single partner is called monogamy.
Option C:
Homozygous is the condition of having both similar alleles in a diploid cell.
Final answer: A condition, where a certain gene is present in only a single copy in a diploid cell is called hemizygous.