Actually, yes, this is true. Let's look at some examples with the word "all" to see if it agrees with verbs in singular or in plural:
All is lost
All is well
All is arranged already.
All of it is nice
This shows us that "all" agrees with verbs in singular form: the correct answer is a) True.
He received a letter from Jekyll.
Hope that helped u ;)
Depends on the tpoic or genre youre writing about?