Which vowel corresponds to the 'ash' sound?

The 'ash' sound, represented by the symbol æ in the International Phonetic Alphabet (IPA), corresponds to the vowel sound found in words like "cat," "man," and "black." This sound is a near-open front unrounded vowel, which means it is pronounced with the tongue positioned low and towards the front of the mouth, and the lips are unrounded.

When considering the other choices, 'e' typically represents a close-mid front unrounded vowel as found in "bed," which does not have the same open quality as the 'ash' sound. The letter 'i' represents a close front unrounded vowel, as found in "see," also different in quality from the 'ash' sound. The 'ɛ' sound corresponds to the open-mid front unrounded vowel, as in "pen," which is somewhat similar but not the same as 'æ'; it is positioned higher in the oral cavity.

Therefore, 'æ' is specifically the symbol that accurately denotes the 'ash' sound in phonetic transcription, making it the correct answer.