Agenetic carrier is someone who
a. has a defective allele and defective phenotype
b. has a defective allele and normal phenotype
c. has one copy of a defective dominant allele
d. has one copy of a defective allele

The correct answer is option B. has a defective allele and normal phenotype.

Explanation:

Genetic carrier or the hereditary carrier is an organism or a person that has a recessive allele for a particular trait or character (generally mutation) but does not exhibit the trait or any character related to the trait.

The carriers are normal in the sex-linked characters in comparison to the autosomal traits. Females are generally the carrier for sex-linked characters and carry the allele to the next generation.

Thus, the correct answer is option B. has a defective allele and normal.