The correct option is B 23 years
Ayush's present age =10 years.
His mother's present age =(10+20) years =30 years.
Ayush's father's present age =(30+5) years =35 years.
Ayush's father's age at the time of Ayush's birth =(35−10) years =25 years.
Therefore Ayush's father's age at the time of marriage =(25−2) years =23 years.