Final answer:
The combing form 'Myo-' denotes muscle, making the correct option 4) Myoc-. It is used in terms such as myocardial and myofibrils.
Step-by-step explanation:
The combing form of a word part that means "muscle" is My/o-. The correct option from the given choices is number 4) Myoc-. This prefix is used in medical terms related to muscles. For example, myocardial infarction involves the word root 'myoc', which refers to the muscle of the heart (myocardium). Similarly, myofibrils and myofilaments are structures within muscle cells that perform the function of contraction and are incorporated with the root 'myo' indicating their relation to muscle tissue.