Genetic characteristics that we can't control include __ A. height and amount of muscle fibers B. amount of muscle fibers and heart rate C. heart rate and flexibility D. flexibility and amount of daily exercise

## Step 1<br />The question is asking about the genetic characteristics that we cannot control. These characteristics are determined by our genes and are not influenced by our lifestyle or environment.<br /><br />## Step 2<br />Option A includes height and the amount of muscle fibers. Both of these characteristics are determined by our genes. While we can influence our muscle mass through exercise, the number of muscle fibers we have is a genetic characteristic.<br /><br />## Step 3<br />Option B includes the amount of muscle fibers and heart rate. While the amount of muscle fibers is a genetic characteristic, heart rate can be influenced by factors such as stress and physical activity.<br /><br />## Step 4<br />Option C includes heart rate and flexibility. While heart rate can be influenced by factors such as stress and physical activity, flexibility is a genetic characteristic.<br /><br />## Step 5<br />Option D includes flexibility and the amount of daily exercise. While flexibility is a genetic characteristic, the amount of daily exercise is not. It is influenced by personal choices and lifestyle.