What characteristic defines closed syllables in the CVC pattern?

Closed syllables are characterized by having a short vowel sound, which occurs in a CVC (consonant-vowel-consonant) pattern. In a closed syllable, the vowel is 'closed in' by consonants on either side, which typically causes the vowel sound to be pronounced in its short form. For example, in the word "cat," the 'a' is a short vowel because it is surrounded by consonants.

The other options do not accurately describe the nature of closed syllables. Long vowel sounds typically appear in open syllables, where the vowel is not closed by a consonant. Repeated vowel sounds may suggest the formation of different syllable patterns or words entirely and do not apply to the closed syllable definition. Furthermore, closed syllables certainly contain consonants, which is integral to their structure since it's the presence of consonants that leads to the vowel being short.