Explanation:
To understand why option 'A' (ruin) is the correct answer, let's analyze the other options and their meanings:

b) Spoil: This means to diminish the quality or value of something. While the person in question may indeed spoil something, it does not necessarily imply that they will destroy or ruin it. Therefore, this option is not the best fit.
c) Dust: This means to remove dust from a surface. It does not convey the idea of destruction, so it is not the correct answer.
d) Hit: This means to strike someone or something with force, but it does not necessarily imply destruction. While it is possible that the person may physically harm or hit someone, it does not encompass the idea of complete destruction, so it is not the best choice.
e) Engulf: This means to completely surround or cover someone or something. While it conveys a sense of enveloping or overpowering, it does not explicitly describe destruction. Therefore, it is not the most accurate option.

a) Ruin: This means to cause severe damage or destruction to something. It perfectly captures the idea that the person in question will completely destroy the object or person. This option aligns with the given context and is the most appropriate choice.

In conclusion, option 'A' (ruin) is the correct answer because it accurately represents the meaning of "destroy" in the given context.