Poor aerobic capacity can make it difficult to

Poor aerobic capacity can make it difficult to perform certain activities that involve aerobic threshold. Examples of these exercises are brisk walking for 30 minutes, running for 20-30 minutes, or playing badminton.

Aerobic capacity refers to the ability of the cardiorespiratory system to work together in synchronicity in able to supply the body with the enough oxygen it needs to perform muscle contractions. This process happens through the circulatory system when the blood flows from the heart to the lungs and into the different parts of the body. Having a poor aerobic capacity means that the cardiorespiratory and circulatory systems are not efficiently working together leading to poor performance in different activities.

Aand b would both be correct