Solving it mathematically,
Suppose the man travelled 'x' distance before meeting the carriage. Let the speed of carriage be 'S'.
Equation 1: Since the man arrived at the station 90 mins early therefore he should have reached his house 90 mins earlier if he would have traveled the whole distance by carriage, but he only reaches his house 60 mins earlier. This 30 mins delay is because of slower speed of walking which can be expressed as:
Time taken now: x/4+8/S
Time taken in normal case: (x+8)/S
therefore; (x/4+8/s) - (x+8)/S = 1/2 thus
x(S-4)/4S = 1/2Equation 2: Since carriage is running on time therefore it would have reached train station in time. The work done in 90 mins extra can be accounted by time spent for travelling 'x' distance by man + time that would have been spent had the carriage gone the whole distance to train station.
Therefore; x/4 +x/S = 3/2 thus
x(S+4)/4S = 3/2Dividing the two equation: (S-4)/(S+4) = 1/3 and thus S = 8km/hr
Substituting 'S' in one of the above equation, x = 4km and therefore total distance between train station and the house is 12km.
Therefore A option is correct.