Which term refers to the sex of a person or organism?

The correct term that refers to the sex of a person or organism is "gender." Gender encompasses the qualities, roles, behaviors, and identities that society considers appropriate for males and females. While "sex" typically refers to the biological differences between male and female organisms, gender is more associated with the social and cultural aspects of being male or female.

In biological and anthropological contexts, understanding the distinction between sex and gender is essential. Sex is often classified based on physical attributes such as reproductive organs and chromosomes, whereas gender involves identity and societal roles.

The other terms mentioned in the question do not accurately define the sex of a person or organism. Age refers to how long a person or organism has lived, race pertains to classifications based on physical characteristics and ancestry, and species denotes a group of organisms that can interbreed and produce viable offspring. None of these terms relate specifically to the concept of sex as it is understood in both biological and social contexts.