Assertion: Alkynes are more reactive towards nucleophilic addition reaction as compared to alkenes. Reason: Alkynes contain two pi bonds, while alkenes have only one bond.

In the case of alkynes, the carbon atom is sp hybridized thus more electronegative, more s-character thus nucleophile can easily attack it whereas in the case of alkene it is 2 sp hybridized only and less s-character as compared to the alkyne. Hence, the correct option is (b).