A n environmental stressor could be;
the weather, too hot, say a heatwave, which can cause heat stroke, dehydration etc, or too cold, where vulnerable people may freeze to death, or develop frost bite etc.
So, some characteristic part of where we live which may, under certain conditions cause difficulty for us or some other living being.
The most logical cause would be an infection.
most likely cellulitis
The option which is not one of the five vegetable categories is C. leafy.
Here are the five vegetable categories:
1. dark-green: broccoli, spinach, kale...
2. red and orange: tomatoes, carrots, squash, pumpkin, sweet potatoes...
3. beans and peas
4. starchy: corn, potatoes, green peas...
5. other: zucchini, peppers, Brussel sprouts...