Yes, A. Mets are actually "metabolic equivalents". See
(Broken Link Removed) If you are burning 5 Mets exercising, you are burning up Calories at 5 times the rate you burn them when just resting.
Yes, A is the correct answer. The basic unit that describes energy costs in terms of oxygen consumption is MET, which stands for Metabolic Equivalent of Task. A MET is the ratio of an individual's working metabolic rate compared to their resting metabolic rate. One MET is equivalent to the amount of oxygen consumed while sitting at rest.
