If you're aerobically fit, you can
a. run a marathon without experiencing fatigue.
b. quit your normal exercise routine without any negative effects.
c. sustain a regular routine of exercise for 30-60 minutes with minimal fatigue.
d. lift very heavy weights without injuries to your joints.

The question is asking what you can do, if you are earobically fit. These are the options: A. run a marathon without experiencing fatigue. - this is not possible. Even the most experience marathon runners experience fatigue, as marathons are very extreme activities B. quit your normal exercise routine without any negative effects. - this is also not true. Being aerobically fit does not stay for life, but you have to practice it, so you have to keep your routine. C. sustain a regular routine of exercise for 30-60 minutes with minimal fatigue. - yes, this is the correct option! This is doable i you're fit, but not if you're note. D. lift very heavy weights without injuries to your joints. - this is not true- lifitng heavy weights is always a strain on your body, whether you're fit, or not

“d” is the answer to the question