Which of the following statements is true about sex chromosomes?

Sex chromosomes are crucial in determining the genetic sex of an individual and can influence various physical traits associated with that sex. In many organisms, such as humans, the presence of different sex chromosomes (like X and Y in mammals) leads to the expression of genes that contribute to sexual characteristics, including reproductive organs, secondary sexual traits, and even some behavioral aspects.

For example, certain genes located on the Y chromosome are directly involved in male sex determination, while multiple genes on the X chromosome can influence traits that are sexually dimorphic, meaning they differ between males and females. This includes traits such as body size, distribution of muscle and fat, and even certain aspects of behavior.

In contrast, the other statements do not accurately reflect the nature of sex chromosomes. They are not always identical, as individuals typically have either two X chromosomes (female) or one X and one Y chromosome (male) in species like humans. Furthermore, sex chromosomes have a significant influence on an organism's development, specifically in determining sexual characteristics, contrary to the notion that they do not affect offspring development. Lastly, sex chromosomes are not considered part of the autosomal set, which consists of non-sex chromosomes that are the same in both sexes.