Which is the correct form of idiom used in the sentence?

The correct answer is: Option 3.

Key Points

• The word "idiom" refers to a phrase or expression that has a figurative, or sometimes literal, meaning different from the literal meanings of the individual words. 
  • Example: "Kick the bucket" is an idiom that means "to die".
• "ABC" in this context means the basic or elementary knowledge of a subject. (प्रारंभिक जानकारी)
  • Example: She doesn't even know the ABC of cooking.
• Hence, the correct form of the idiom is "He doesn't know the ABC of mathematics".

Therefore, the correct answer is: Option 3.

Additional Information

Here are the other options explained along with their Hindi meanings and example sentences:

• Option 1: He don't know the ABC of mathematics.
  • Example: He don't know the ABC of mathematics. (Incorrect usage of "don't" instead of "doesn't")
• Option 2: He doesn't knows the ABC of mathematics (:
  • Example: He doesn't knows the ABC of mathematics. (Incorrect usage of "knows" instead of "know")
• Option 4: He do knows the ABC of mathematics :
  • Example: He do knows the ABC of mathematics. (Incorrect usage of "do knows" instead of "doesn't know")