Final answer:
A thin fibrous cap is characteristic of a vulnerable plaque, which is more prone to rupture compared to other plaque types.
So, the correct answer is B. Vulnerable plaque.
Step-by-step explanation:
The thin fibrous cap is seen in vulnerable plaque. A vulnerable plaque is a type of atherosclerotic plaque that has a thin fibrous cap overlying a large lipid core. This makes it more prone to rupture, which can lead to thrombosis and subsequent blockage of the artery, potentially resulting in a heart attack or stroke. In contrast, a stable plaque has a thick fibrous cap and a smaller lipid core, making it less likely to rupture. Calcified plaques have a hard calcium shell, and ruptured plaques are those that have already broken open.
So, the correct answer is B. Vulnerable plaque.