Which of these sentences is the most grammatically correct?
a. This page has been left blank intentionally.

b. This page has been intentionally left blank.

c. This page has intentionally been left blank.

Thanks!

All work, but the second one is best.

This is based on:

(1) the adverb being nearest to the verb (left)
(2) not dividing the auxiliary pairing (has been) and the participle (left), which are best left side by side

Thanks for the reply. I will "intentionally" use this rule in the future!