The correct meaning for the idiom "Time flies" is A: Time moves quickly. This common expression is used to convey the feeling that time passes very rapidly, often unexpectedly fast. It's typically used when someone is enjoying themselves, is very busy, or is reflecting on a period that seemed to pass in a blink of an eye.
The phrase captures the subjective experience of time, where moments or periods can feel much shorter than they actually are. For example, if you're having a great time at a party, you might exclaim, "Wow, time flies when you're having fun!" or if you look back at your childhood, you might remark, "It feels like only yesterday, time really flies."
It's a simple yet powerful idiom that highlights the fleeting nature of time, especially when one is engaged or content, making it a universal sentiment.