Final answer:
The best statement demonstrating an understanding of hypertrophic cardiomyopathy (HCM) is that the client's heart muscle has become thick, making it harder for blood to pump.
Step-by-step explanation:
The best statement demonstrating an understanding of hypertrophic cardiomyopathy (HCM) is option b) "My heart muscle has become thick, making it harder for blood to pump." In HCM, the heart muscle becomes abnormally thick, causing it to stiffen and restrict blood flow. This can lead to symptoms such as chest pain, shortness of breath, and an irregular heartbeat. The other options do not accurately describe the effects and understanding of HCM.