According to the Doubling Rule, what must you do with a one syllable word before adding a vowel suffix?

The Doubling Rule is essential in understanding how to properly add vowel suffixes to single-syllable words. The focus here is on the consonant that comes after a single vowel in a one-syllable word. According to this rule, when a one-syllable word ends with a consonant that follows a single vowel—particularly when that syllable is accented—you must double the final consonant before adding a vowel suffix. This is particularly relevant in words like "run," where the final 'n' is doubled to form "running."

In contrast to the other options, they do not align with the Doubling Rule framework. The suggestion to double the last vowel does not apply, as the rule specifically addresses consonants. Changing the ending to a suffix before doubling the consonant is not a correct stipulation within the rule itself; the focus is on doubling the consonant after determining the vowel base. Lastly, adding an extra consonant doesn’t appropriately delineate what occurs in the application of the Doubling Rule. Thus, the correct understanding centers around the consonant following the vowel in the context of one-syllable accented words, making the approach suggested by the Doubling Rule clear and effective.