Environment factors can influence natural selection because they can increase or decrease

Heres the answer

environmental factors can influence natural selection by increasing or decreasing the amount of genetic variation in a population. Increasing genetic diversity usually occurs via mutation, whereas decreasing genetic diversity can occur when that particular allele reduces the chances of individuals with that trait to reproduce (e.g. the organism often dies before breeding). 

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.