I am assuming that the underlined word is "malicious" due to the options provided.
Answer:
The best word to replace "malicious" is:
a. evil
Step-by-step explanation:
The adjective "malicious" refers to something or someone that has the intention of causing harm, that has malice. "Evil" as an adjective refers to someone or something that is wicked, immoral. An evil person causes harm. An evil person has malice. Thus, we can say an evil person is malicious. Following that train of thought, we can safely say that option A. evil is the best word to substitute "malicious" is the sentence.