The correct answer is A. No, different sections of the cell's DNA are turned on, causing heart cells to have different characteristics from brain cells.
Explanation: Heart cells (cardiomyocytes) and brain cells (neurons) have distinct functions and characteristics, even though they originate from the same genetic material in the DNA. The differentiation of these cells occurs due to the expression of different sets of genes, which leads to the development of specialized functions suitable for either the heart or the brain.