Which statement applies to the effects of exposure to harmful substances during embryonic life?
1. During the first two weeks, exposure will usually cause death of the embryo.
2. Organs or body structures may be altered by exposure during the first two months.
3. The effects of exposure depend on the stage of development at the time of exposure.
4. Metabolic abnormalities usually follow exposure to teratogens.
1, 3
2, 4
1, 2, 3
2, 3, 4