Final answer:
Fetus exposure to amphetamines in utero can lead to negative health outcomes such as respiratory distress; it is unlikely to cause increased intelligence or improved motor skills, nor would it typically decrease the fetal heart rate.
Step-by-step explanation:
A fetus exposed to amphetamines in utero is at risk for various adverse effects. Amphetamines can cross the placental barrier and have the potential to cause negative outcomes such as preterm birth, low birth weight, and withdrawal symptoms, which may present as respiratory distress in the newborn. Based on the information provided and the known effects of similar stimulants, such as cocaine and methamphetamine, a fetus exposed to amphetamines would not experience increased intelligence or improved motor skills, nor would there likely be a decrease in heart rate, which is more commonly associated with depressant drug exposure.
Therefore, the correct answer to the question 'Fetus exposed to amphetamines in utero' with the options provided would be 'B. Respiratory distress'. It is important to note that the use of amphetamines during pregnancy is risky and can lead to various health complications for both the mother and the fetus.