Test-tube fertilization and artificial insemination are a. nonviable contraceptive methods. b. nonnatural methods of conception. c. inherently distinct methods of conception. d. used only in eastern civilizations

The correct answer is C.
Test tube fertilization refers to the process of fertilizing an egg outside the body. Through an in vitro procedure, the egg is combined with the sperm and this results in the fertilization.
Artificial insemination refers to the practice of introducing healthy active sperm in the uterus or cervix of the female. This is done specifically on the day of the female's ovulation, increasing the possibilities of the sperm fertilizing the egg.
These two methods are widely used with success, therefore, they cannot be described as nonviable. Also, they are not used only in Eastern civilizations.