Directions: Fill in the blank by choosing the right form of the given four alternatives.

If he is honest, he _______.

This is a first conditional sentence describing a real possibility in the present/future. The structure is: If + present simple, ... will + base verb. 'If he is honest' uses present simple, so the result clause uses 'will prosper' (will + base verb). First conditionals express likely or possible future results based on present conditions.