Disease of heart muscle:Group of answer choicesCardiomegalyCardiomyopathyAortic stenosisEndocarditisArteriolitis

The disease of heart muscle is Cardiomyopathy.

Here's why:

1. Cardiomegaly is a condition where the heart is enlarged, but it's not a disease of the heart muscle itself. It's often a symptom of other conditions.

2. Cardiomyopathy is a disease of the heart muscle. It makes it harder for your heart to pump blood to the rest of your body.

3. Aortic stenosis is a disease of the heart's aortic valve, not the heart muscle.

4. Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves.

5. Arteriolitis is an inflammation of the small arteries, not a disease of the heart muscle.

So, the correct answer is Cardiomyopathy.