Actually it is the females the mostly build the nests the males will help build it sometimes both males and females will build it but typically it is females and that goes for all birds.
"Females typically build nests, but sometimes both parents or just the male"
B. Mutations cause a person's body cells to divide uncontrollably. There isn't a signal for cells to stop dividing, so this can cause cancer because cancer cells won't stop dividing without this signal.