Answer:
The correct answer will be- a biological control agent
Step-by-step explanation:
Biological control is the method of controlling the harmful or useless organism using biological agents. The harmful organism which should be removed includes the pests, weeds, mites and other organisms whereas the agents which control this biological organism are called control agents.
The relationship of control depends on the ecological relationship between two organisms which could be prey-predator, herbivory and parasitism.
In the given question, since the goat help, the fields get rid of kudzu which involves the herbivory interaction and helps control the kudzu therefore, a biological control agent is the correct answer.