Final answer:
In English, 'which' isn't traditionally used to refer to people. However, the use of gender-neutral pronouns such as 'they/them/their' is becoming more common, especially when the gender is unknown, not important, or when a person prefers these pronouns. If in doubt, asking a person's pronoun preference is recommended.
Step-by-step explanation:
The question is about the correct usage of pronouns to refer to a person, particularly in relation to gender identity. In English grammar, it has been common to use 'he' or 'she' for specific genders and 'it' for non-human entities. Traditionally, 'which' would refer to objects or things, not people.
However, as societal understanding of gender expands, the language also evolves. Pronouns like 'they/them/their' are now often used as gender-neutral singular pronouns to refer to a person whose gender is unknown or not relevant, or who prefers these pronouns. If unsure, it is best to ask the person's pronoun preference or to use their name.
Lastly, about generic nouns like doctor, athlete, and scientist, and indefinite pronouns like anyone, each, and everyone, earlier they took the singular pronouns 'he/him/his'. But now, they can be replaced by 'they/them/their' when the gender is not known or important.
Learn more about Pronoun Use