Differences between endocrine and exocrine glands include

Explanation:

1. Endocrine glands are those glands which secretes its products (example hormones) directly into the blood.  

Example: The adrenal gland: secretes adenaline directly into the blood.

2. Exocrine gland are those glands which secretes its products (example enzymes) into ducts that finally lead to the target tissue.  

Example:  As salivary gland secretes saliva enzyme into the collecting duct.

Note: Pancreas gland performs both endocrine as well as exocrine functions.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).