What role is とも playing in "それとも自殺？"


The sentence pair

> それは殺人だったの？それとも自殺？

translates to

> Was it a murder or a suicide?

Can somebody help explain what role とも is playing in the second sentence?




As was pointed out in the comments: それとも is a single word
(<https://jisho.org/word/%E5%85%B6%E3%82%8C%E5%85%B1>).




As was pointed out in the comments: それとも is a single word
(<https://jisho.org/word/%E5%85%B6%E3%82%8C%E5%85%B1>).

