**Core Concept**
The question is testing the ability to identify the underlying cause of isolated prolongation of Activated Partial Thromboplastin Time (APTT) in a patient with a history of recurrent abortions. This requires an understanding of the coagulation cascade and the factors that contribute to APTT prolongation.

**Why the Correct Answer is Right**
Isolated prolongation of APTT suggests a problem in the intrinsic or common pathway of the coagulation cascade. In a patient with a history of recurrent abortions, one of the most likely causes is the presence of antiphospholipid antibodies. These antibodies can activate the intrinsic pathway, leading to APTT prolongation. Antiphospholipid antibodies also have a prothrombotic effect, which can contribute to the patient's history of recurrent abortions.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the patient's history of recurrent abortions. While liver disease can cause prolongation of APTT, it is not the most likely cause in this scenario.

**Option B:** This option is incorrect because it does not explain the patient's history of recurrent abortions. Factor VIII deficiency is a cause of prolongation of APTT, but it is not related to the patient's history of recurrent abortions.

**Option C:** This option is incorrect because it does not address the patient's history of recurrent abortions. While warfarin can cause prolongation of APTT, it is not the most likely cause in this scenario.

**Clinical Pearl / High-Yield Fact**
In patients with a history of recurrent abortions, isolated prolongation of APTT should raise suspicion for the presence of antiphospholipid antibodies. These antibodies can be detected through laboratory testing and can have significant implications for the patient's management and pregnancy outcomes.

**Correct Answer:** D. Antiphospholipid syndrome.