For Teratogens That Show a Dose-Response Relation

For teratogens that show a dose-response relation:

A) any level of exposure to the teratogen causes an equivalent likelihood of a defect.
B) the greater the exposure to the teratogen, the greater the likelihood of a defect.
C) the greater the exposure to the teratogen, the lesser the likelihood of a defect.
D) exposure to the teratogen can be beneficial at low levels.