What does the idiom 'To leave no stone unturned' mean?

Correct option is A

Option (a) is the correct meaning of the given idiom.
Given Idiom: To leave no stone unturned — to make every possible effort, examining all possibilities to achieve a goal; to search thoroughly without overlooking anything (Hindi: हर संभव कोशिश करना / पूरा-पूरा प्रयास करना).
Example: The team left no stone unturned to find the missing evidence.
Other related idioms and their meanings:
· Go the extra mile — do more than is required (Hindi: अतिरिक्त प्रयास करना).
· Bend over backwards — make a great effort to help (Hindi: बहुत ज़्यादा कोशिश करना).
· Move heaven and earth — do everything possible (Hindi: आसमान ज़मीन एक कर देना).
· Spare no effort — make every possible effort (Hindi: कोई कसर न छोड़ना).