* A. When it rains it pours: This means that when bad luck happens, it tends to happen in large quantities all at once. It's a figurative expression, not literal, making it an idiom.
* B. It became a hot potato issue: This refers to a situation that is difficult or unpleasant to deal with. The image of a hot potato you don't want to hold is metaphorical, making it an idiom.
* C. She cut corners: This means someone took shortcuts or did something in a less thorough way. The act of literally "cutting corners" wouldn't make sense in this context, highlighting the figurative nature of the idiom.
Idioms are expressions that have a meaning different from the literal meaning of the words used. They are common in everyday language and often convey a specific cultural understanding.