Which statement is true about coroutines?

The statement that a coroutine may or may not execute is accurate because it reflects the nature of coroutines in Kotlin. Coroutines are designed to simplify asynchronous programming, but they are not guaranteed to run immediately or at all. This characteristic allows developers to launch coroutines in a non-blocking fashion; they can be used to perform tasks in a background thread, but they can also be canceled or delayed based on certain conditions or program states.

For instance, a coroutine may not execute if it is canceled before it has a chance to start or if the scope in which it was launched is no longer active. This flexibility is an important part of coroutine design, as it allows for efficient resource handling and better responsiveness in applications.

The other statements do not accurately describe coroutines' behavior. Coroutines can be canceled once started, can run on multiple threads (not just the main thread), and do not necessarily execute every task on the same thread, as they are designed to be lightweight and to facilitate concurrency by allowing multiple coroutines to run in parallel or sequentially across different threads.