か

「か」 between two words means 'or': you pick one. 「コーヒーか紅茶」 (coffee or tea). It can join nouns, verbs and adjectives. To stress that you must choose, say 「AかBか」: 「行くか行かないか」 (whether to go or not).

Keep the three noun-joining particles apart:

•「と」: lists everything; both A and B.

•「や」: a few examples, and there are more.

•「か」: a choice; A or B.

This 「か」 sits between words, which is different from the 「か」 at the end of a question.