Alternate question
In English when we question a person about two alternatives, we say “Is it X or (is it) Y?” In Japanese one forms the questions as if they were independent - yet through intonation they become a single compound sentence.
Optionally, soretomo (meaning "alternatively" or "or") may be used between the two alternates, especially when the alternates are complex and lengthy. While in English "or" is always used in an alternate question, soretomo is far less common.
Examples:
東京にありますか、大阪にありますか。
Tookyoo ni arimasu ka, Osaka ni arimasu ka?
Is it in Tokyo or in Osaka?
右ですか、左ですか。
Migi desu ka, hidari desu ka?
Is it right or left?