Aball rolling at 15 m/s rolls off a cliff and lands on the ground 3 seconds later.

OK.  It would be best if you were not standing 45 meters (148 feet) from
the edge of the cliff, because that where the ball will land.  At that instant,
the ball will be moving 15 m/s horizontally and 29.4 m/s vertically, for a total
speed of 33 m/s (almost 74 mph) when it beans you.

The cliff is 44.1 m (about 145 feet) high.
 
Did you have a question to ask ?

Ithink d is the right answer. hope this !