Question: farmer brown has sprayed his fields to kill the grasshoppers eating the grass in his pastures. predict what will happen to the other living things in this food chain. will their number increase or decrease and why?

In a grassland food chain, grasshopper feeds on grasses is a herbivore, primary consumer. Grasshopper in turn eaten by secondary consumer such as frog. Frog is being eaten by snake, a tertiary consumer. By killing grasshopper, the food chain will gets disturbed. Thus, population of secondary consumer and tertiary consumer will decrease in absence of their food and the population of grasses will increase in absence their consumers, grasshoppers.  

the answer is the last option or letter d)