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.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c