All 3 Uses

acknowledge
in
Flags of Our Fathers
(Auto-generated)

As Thomas rushed past him, he yelled a greeting and saw Chick's hand and eyes move, acknowledging him.†
Chpt 7. *

acknowledging = recognizing
He would stand, acknowledge the introduction with a prodigious yawn, which invariably brought a mass response from the audience, then sit down and go back to sleep.†
Chpt 16.

acknowledge = recognize
Acknowledging the cheers of a Rose Bowl crowd at halftime; dedicating another statue; appearances as a "mystery guest" on TV; another speech; waving from the convertible to the crowds lining the parade—he rarely said no. One minute the hero, and back home the airline clerk, an employee in his wife's travel agency, and finally a janitor.†
Chpt 19.

acknowledging = recognizing

Definitions:

(1) (acknowledge as in: acknowledge her or the truth)
express recognition or appreciation of someone or something; or to admit or express something
(2) (meaning too rare to warrant focus)
Specialized senses include sending an "acknowledgement" (letter or other message) to indicate that something was received and the "acknowledgements" section at the beginning of a book where an author recognizes and thanks other people who helped in creating the book or ideas contained in it.