Which of the following pairs illustrates a vowel-r combination?

The correct answer illustrates a vowel-r combination, which occurs when a vowel is followed by the letter 'r' in the same syllable, wherein the 'r' influences the sound of the vowel. In the pair "bread" and "nail," both words contain a vowel followed by an 'r' sound, meaning that the 'r' alters the sound quality of the preceding vowel. In "bread," the 'ea' creates a short vowel sound that is affected by the 'r' in the subsequent syllable.

In contrast, other choices do not demonstrate this vowel-r combination. For instance, "shape" and "shine" do not involve an 'r' following the vowel, resulting in a straightforward vowel sound. Similarly, "button" and "napkin" do not include a vowel-r pairing, as their vowel sounds are not followed by an 'r.' Lastly, "doctor" and "dollar" also lack a direct vowel-r combination in the syllables as 'o' and 'a' are not followed by an 'r' that directly alters their sound. Thus, the pair "bread" and "nail" accurately represents the vowel-r interaction.