Answer: d. all of the above
Explanation:
All of the above can help children improve their phonological awareness.
Using concrete objects like toy letters can enable the kid know how to better move letters around to pronounce certain words.
Gestures learned to represent the manipulation of some words will also help the child develope phonological awareness by relating those gestures to other words.
Finally, visually aiding the child by showing the images of words being manipulated can be beneficial as well because they will learn to associate new words with the right sounds and pronounce them as they should.