How is gender expression defined?

Gender expression is defined as the way a person presents themselves in terms of their gender. This can include a variety of aspects such as clothing, hairstyle, behavior, and mannerisms that communicate a particular gender identity to others. It reflects how individuals choose to express their gender to the world around them, which can align with or differ from societal norms and expectations associated with their assigned sex at birth.

The other options highlight different concepts related to gender but do not accurately define gender expression. Societal expectations of gender pertain more to the norms and roles dictated by culture, while biological characteristics focus on the physical attributes related to sex rather than the individual's expression of gender. The psychological understanding of gender identity refers to an individual's internal perception of their gender, which may not necessarily manifest in their outward expression. Thus, option B correctly captures the essence of how individuals showcase their gender to others.