Which process occurs in a human muscle when it gets forced to make ATP without oxygen?

C: Lactic acid fermentation

Explanation:

Cellular respiration without oxygen is called anaerobic respiration. ETS (or electron transport chain) reactions happen as the last step of aerobic cellular respiration, therefore it is incorrect.

Lactic acid fermentation is a metabolic process by which glucose and other six-carbon sugars are converted into cellular energy and the metabolite lactate, which is lactic acid in solution. It is an anaerobic fermentation reaction.