Offsprings receive valuable qualities from both parents in: 
a) Cross pollination
b) Self pollination
c) Wind pollination 
d) Insect pollination 

Dear student, offsprings receive valuable qualities from both parents in cross pollination in which the pollens from the anther of one flower get transfered to the stigma of the flower of different variety. This results in the formation of hybrid. Hence option a is correct. Thanks and regards