Option 1 suggests that the sex ratio is about the number of women per square kilometer in relation to males. This is not an accurate definition of sex ratio. Sex ratio is about the number of females per 1000 males, not the number of women per square kilometer.

Option 3 suggests that sex ratio is about the number of women per state in relation to males. This is also not an accurate definition. Sex ratio is a broader concept and is not specific to a particular state.

Option 4 implies that sex ratio refers to the number of men in an area. This is incorrect. Sex ratio specifically looks at the proportion of females to males, not the number of men.

Option 2 correctly states that sex ratio refers to the number of females per 1000 males. This is the accurate definition of sex ratio.