A preschool teacher shows a group of children pictures of everyday objects. Below each picture is printed the letter of the alphabet that corresponds to the word's initial sound. As the teacher points to each picture, she names the object, then she points to the letter underneath it and says the sound it makes. The teacher invites the children to repeat the sound with her. This activity is likely to contribute to the children's reading development primarily by:

A) illustrating the concept of word boundaries
B) focusing on auditory discrimination skills
C) introducing the concept of onset and rime
D) demonstrating that phonemes are represented by letters