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'.

Problem: the racing magic takes 50 seconds to circle the racing track once . the charging bull makes 40 rounds of the track in an hour . if they left the starting point together , how many minutes will it take for them to meet at the starting point for the second time ? 
Options: a ) 3 , b ) 6 , c ) 9 , d ) 12 , e ) 15
e

Problem: what is the angle between the minute hand and the hour hand when the time is 1540 hours ? 
Options: a ) 150 , b ) 160 , c ) 140 , d ) 130 , e ) none
d

Problem: two carpenters , working in the same pace , can build 2 desks in two hours and a half . how many desks can 3 carpenters build in 4 hours ? 
Options: a ) 2.4 . , b ) 4.8 . , c ) 4.2 . , d ) 5.5 . , e ) 6.4

b