Assertion: Toluene on Friedel Crafts methylation gives o- and p- xylene.

Reason: CH3 -group bonded to benzene ring increases electron density at o- and p- position.

1.  Both assertion and reason are true and the reason is the correct explanation of assertion.

2.  Both assertion and reason are true and the reason is not the correct explanation of assertion.

3.  Assertion is true but the reason is false.

4.  Assertion is false but the reason is true.

Hint: CH3 group is an electron-donating group
 
Toluene has -CH3 group attached to benzene. -CH3 group activates the benzene for the attack of an electrophile.
 
In the resonating structure of toluene, electronic density is more on ortho and para position.
 
Hence, substitution takes place mainly at these positions. Thus, both assertion and reason are true and the reason is the correct explanation of assertion.