a. This book resembles to that.
b. Have you signed that contract?
c. A modest man does not boast of his merits.
d. He carefully investigated into the case.
Identify the correct sentences.

The correct answer is Option B (Only b and c).

Key Points:
• 'Resemble' is a transitive verb and takes no preposition (it is 'resembles that', NOT 'resembles to that').
• 'Investigate' is a transitive verb that directly takes an object without 'into' (it is 'investigated the case', NOT 'investigated into the case').
• 'Signed that contract' is perfectly correct (sign takes direct object).
• 'Boast of' is the correct fixed prepositional idiom (to boast of one's achievements/merits).
• Option 2 (Only b and c).
• Sentence a is incorrect due to superfluous 'to'.
• Sentence d is incorrect due to superfluous 'into'.
• Sentences b and c are completely correct.
• Key Takeaway: Resemble and investigate do not take prepositions; boast takes 'of'. Sentences b and c are correct.