Final answer:
In Python, the symbol '#' is used to start a comment. Comments are utilized for explanation and temporarily disabling code.
Step-by-step explanation:
The symbol that marks the beginning of a comment in Python is option c) #. In Python, adding a # symbol at the beginning of a line indicates that the entire line should be treated as a comment and not be executed as code. Comments are useful for explaining code, making notes for yourself or others, or for temporarily disabling code without deleting it.