**Core Concept**
Oxytocin infusion is used to induce or augment labor by stimulating uterine contractions. However, excessive uterine contractions can lead to fetal distress and other complications. Therefore, monitoring the frequency of contractions is crucial to prevent these adverse effects.

**Why the Correct Answer is Right**
The correct answer is 5 contractions consistently every 15 minutes. This is because oxytocin infusion should be discontinued if there are more than 5 uterine contractions in a 10-minute period, which is equivalent to 5 contractions in a 15-minute period. This guideline helps prevent excessive uterine stimulation, which can lead to fetal distress and other complications. The mechanism behind oxytocin's action involves stimulation of uterine smooth muscle cells through oxytocin receptors, leading to contraction.

**Why Each Wrong Option is Incorrect**
**Option A:** Discontinuing oxytocin infusion at 3 contractions consistently every 15 minutes is too early, as this frequency is still within the normal range.
**Option B:** Continuing oxytocin infusion at 7 contractions consistently every 15 minutes is incorrect, as this frequency is higher than the recommended limit and may lead to fetal distress.
**Option C:** Discontinuing oxytocin infusion at 2 contractions consistently every 15 minutes is too early, as this frequency is well below the normal range and does not require oxytocin discontinuation.

**Clinical Pearl / High-Yield Fact**
A useful mnemonic to remember the oxytocin infusion guidelines is "5 in 10" or "5 in 15," which stands for 5 contractions in a 10-minute period or 5 contractions in a 15-minute period, respectively.

**Correct Answer:** B. 7