The time it takes for the object in projectile motion to be in air is calculated through the equation,
time of flight = 2v₀sinθ/g
If all else are equal except for θ then, we compare their sin values.
sin(30°) = 0.5
sin(60°) = 0.866
Since the value of sin60° is greater than the value of sin30° then, projectile motion fired at an angle of 60° will spend more time in air.
The answer is the last choice.