There Are Three Children Aged Three,four,and Five in a Room

Multiple Choice

There are three children aged three,four,and five in a room.If another four-year-old child enters the room,what will happen to the mean and variance?

A) The mean will stay the same,but the variance will increase.
B) The mean will stay the same,but the variance will decrease.
C) The mean and variance will both stay the same.
D) The mean and variance will both decrease.