When Does an Individual Attain a Flow State

When does an individual attain a flow state?

A) When he/she is barely able to maintain focused awareness on a target.
B) When he/she is barely awake or aware but shows some deliberate movements.
C) When he/she recollects material that is potentially accessible but not currently available to awareness.
D) When he/she thrives in his/her ability to rise to the occasion of challenging tasks.