Several are correct:
Affect males more than females
Can be carried by females
Are always expressed by males
A bit of explanation: sex linked genes are carried on the X chromosome. That’s why it affects males more than females...they only get one x from their mom. Females can be affected IF they receive 2 bad X chromosomes. So with a male, the bad gene on the x is always expressed. Color blindness is a good example of this.
The answer would be 12 because Carbon has 6 Protons, which means that it has the same number of neutrons and electrons.