**Core Concept**
Prolonged seizure after electroconvulsive therapy (ECT) is a serious complication that requires immediate medical attention. The American Psychiatric Association (APA) has established criteria to define prolonged seizure duration to ensure patient safety.

**Why the Correct Answer is Right**
The APA defines a prolonged seizure after ECT as a seizure lasting more than 2 minutes. This duration is considered prolonged because it increases the risk of seizure-related complications, such as status epilepticus, which can lead to brain damage, respiratory failure, and even death. The 2-minute threshold is based on the understanding that seizures that last beyond this duration are more likely to result in significant neurological consequences.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a seizure lasting 1 minute is generally considered normal and is not associated with an increased risk of complications. The APA criteria specifically define prolonged seizure as lasting more than 2 minutes.
**Option B:** This option is incorrect because a seizure lasting 1.5 minutes is still within the normal range and does not meet the APA criteria for a prolonged seizure.
**Option C:** This option is incorrect because a seizure lasting 3 minutes is indeed prolonged according to the APA criteria, but the question asks for the threshold that defines prolonged seizure, not the duration above which it is considered prolonged.

**Clinical Pearl / High-Yield Fact**
When administering ECT, it is essential to monitor seizure duration carefully and take immediate action if the seizure lasts more than 2 minutes to prevent potential complications.

**Correct Answer: D. 2 minutes**