Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
A sex chromosome is a chromosome that determines the sex of an organism. Humans have two sex chromosomes, X and Y . Females have two X chromosomes ( XX ), and males have one X and one Y chromosome ( XY ). An autosome is any chromosome other than a sex chromosome. If a trait is autosomal it will affect males and females equally.


Question: What chromosome determines the sex of an organism?
sex chromosome
X and Y.