The correct option is A 3
To find out how many sweets Gayathri has left with her, we need to divide 21 by 9.
If Gayathri gives 9 sweets to one of her friends, she has 21−9=11 sweets left with her.
If she gives 9 out of the 11 sweets that she has, she is left with 11−9=3 sweets.
She cannot give to another friend as she has only 3 sweets.
∴ After distributing 9+9=18 sweets in total to two of her friends, Gayathri is left with 3 sweets.
In other words, the remainder when 21 is divided by 9 is 3.