In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Input: Consider Input: Problem: the speed at which a man can row a boat in still water is 15 km / hr . if he rows downstream , where the speed of current is 3 km / hr , how many seconds will he take to cover 90 meters ? 
Options: a ) 12 , b ) 16 , c ) 17 , d ) 18 , e ) 20

Output: d


Input: Consider Input: Problem: a lady starts from p towards q and realizes that at a point r , if he walks 50 km further he will be at a point s , which is as far away from r as it is from q . what is the distance between p and q if the distance between p and r is half the distance from r to q ? ( assume that p , q , r and s are all on the same straight line ) 
Options: a ) 150 km , b ) 200 km , c ) 250 km , d ) 125 km , e ) 155 km

Output: a


Input: Consider Input: Problem: two cars are traveling in the same direction along the same route . the red car travels at a constant speed of 10 miles per hour , and the black car is traveling at a constant speed of 50 miles per hour . if the red car is 20 miles ahead of the black car , how many hours will it take the black car to overtake the red car ? 
Options: a ) 0.1 , b ) 0.5 , c ) 1 , d ) 1.2 , e ) 2


Output: b