Correct Answer - Option 4 : Most of the accidents involving two wheelers take place on roads having scanty traffic.
The given passage refers to a part of the total number of accidents. There is no information about how and when the rest of the accidents take place. Hence, neither choice (1) nor (5) can be concluded.
The passage has no reference to the speeds at which vehicles are driven on roads having heavy traffic. Also the words "mostly on the roads having scanty traffic" does not rule not two wheelers being driven at 50 km/hr and above speeds on roads having heavy traffic. Hence, (2) cannot be concluded.
Driving at speeds above 50 km/hr does not necessarily mean that the driver is reckless. Hence, (3) cannot be concluded.
Since it is said that generally accidents involving two wheelers take place when they are driven at speeds above 50 km/hr and they are driven at the speed on roads having scanty traffic, it can be concluded that most of such accidents take place on roads having scanty traffic.
Hence, (4) can be concluded.