The effects of teratogens select one: a. are predictable and straightforward. b. are usually the most serious during the fetal period. c. vary with the age of the organism at the time of exposure. d. are always detectible at birth.

The right answer is C) Vary with the age of the organism at the time of exposure.

Conventionally, teratogenic drugs have been defined as drugs that can induce visible malformations in newborns, which may interfere with the placement of embryonic organs. These effects are mainly related to exposures in early pregnancy (the period during which the risk is greatest corresponds to the first trimester of pregnancy).

answer///multiple alleles;