'He is a man of straw'.Here 'man of straw' means-

A a man of strong morality

B a very active person

C a rich man

D a man of no substance

Correct Answer: Option D

man of straw(অপদার্থ লোক /অস্তিত্বহীন লোক ) idiom-টির অর্থ a man of no substance