It’s b because you know it is
It mean how are you but you can say how are you doing to and then u said good how are u
You should put "they", "he", or "she", in front of the word stretching to make it third person.
1.) They were stretching.
2.) He was/ is stretching.
3.) She was/is stretching.
Hope that helps.
The adjective is often and the adverb is reads.