Which of the following words demonstrates the rule of doubling the final consonant?

The word "hopped" illustrates the rule of doubling the final consonant because it is a verb that ends in a single consonant preceded by a single vowel when adding a suffix that begins with a vowel. In this case, "hop" ends with "p," which is preceded by the vowel "o." Therefore, when forming the past tense, the final "p" is doubled before adding "ed" to adhere to the spelling rule.

This doubling occurs in cases where the final consonant is flanked by a vowel and at least one consonant in a stressed syllable, which maintains the pronunciation of the vowel sound in the base word. The other words do not exhibit this pattern: "hoping" does not involve a past tense form; "walked" ends with a consonant that does not require doubling; and "fished," like "walked," also does not follow the doubling rule as the base word ends in consonants that do not require this alteration before adding the suffix.