Correct Answer: (4) A — B
Solution:Something or someone that is audacious takes risks in order to achieve something.
For example : an audacious plan to win the presidency. Venturous or venture- some means ready to take risks, daring: young children becoming more venturous in their use of language.
So, audacious and venturous are synonymous. Hence the answer is (4).
Abstruse means difficult to understand.