**Core Concept**
ACE inhibitors are a class of antihypertensive medications that work by blocking the conversion of angiotensin I to angiotensin II, thereby reducing vasoconstriction and blood pressure. However, during pregnancy, they can cause fetal harm by reducing renal blood flow and increasing the risk of oligohydramnios, preterm labor, and fetal growth restriction.

**Why the Correct Answer is Right**
The use of ACE inhibitors in pregnancy is contraindicated due to the risk of fetal harm. This is because ACE inhibitors can cause decreased fetal renal blood flow, leading to oligohydramnios and subsequent pulmonary hypoplasia. Additionally, ACE inhibitors can increase the risk of fetal growth restriction and preterm labor. The mechanism by which ACE inhibitors cause fetal harm is thought to be related to the decrease in fetal renal blood flow, which can lead to a decrease in the production of amniotic fluid.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while other antihypertensive medications may be contraindicated in pregnancy, ACE inhibitors are specifically avoided due to their effects on fetal renal blood flow and the risk of fetal harm.
**Option B:** This option is incorrect because while certain antihypertensive medications may be safer in pregnancy than others, ACE inhibitors are specifically contraindicated due to their risk of fetal harm.
**Option C:** This option is incorrect because while certain antihypertensive medications may be used to treat hypertension in pregnancy, ACE inhibitors are specifically avoided due to their risk of fetal harm.

**Clinical Pearl / High-Yield Fact**
ACE inhibitors should be avoided in pregnancy due to the risk of fetal harm. It is essential to choose alternative antihypertensive medications that are safer for both the mother and the fetus.

**Correct Answer:** A. Lisinopril.