In the following passage some wordshave been deleted. Fill in the blanks with the help of
the alternatives given. Select the most appropriate option for each blank.

Forest fire always (1)_____ by one of two reasons-naturally caused or human-caused. Natural fire is generally (2)_____ by lightning, with a very small percentage (3)_____ by spontaneous combustion of dry fuel such as saw dust and leaves.(4)_____, human-caused fire can happen (5)_____ any numberof reasons.