Desmond sees an attractive woman whom he would like to meet. as he approaches her, his heart starts racing and his pupils dilate. in this situation, is the stressor, and is the stress reaction.

Attractive woman is the stressor

Racing heart is the stress reaction

Explanation:

Anything that causes stress, or tension is a stressor. To deal with the stress, your body will react. In this case, approaching the attractive woman is stressing Desmond out, so she is a stressor. The stress reaction would be the racing heart, which occurs because of the sudden release of hormones in the body. This is your body's way of preparing you to deal with what is causing your stress.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.