“A book lying idle on a shelf is wasted ammunition.”(Para. 4)What is the figure of speech used in this sentence?（）

“A book lying idle on a shelf is wasted ammunition.”(Para. 4)What is the figure of speech used in this sentence?（）
A.Simile.
B.Metaphor.
C.Personification.
D.Analogy.
正确答案：Analogy.