Which sound represents a mid front unrounded vowel?

The sound that represents a mid front unrounded vowel is the one associated with the word "head." This vowel sound is articulated with the tongue positioned in the middle front of the mouth and without rounding the lips, which is the defining characteristic of unrounded vowels.

In this case, the specific sound in "head" represents the mid front unrounded vowel /ɛ/, as in words like "bed" or "red." This contrasts with other vowel sounds in the choices provided. For example, the sound in "fit" is a near-close near-front unrounded vowel /ɪ/, while "eat" features a close front unrounded vowel /i/. Lastly, the vowel sound in "boat" is a diphthong or a back rounded vowel, which does not meet the criteria for a mid front unrounded vowel.

Understanding these characteristics is vital in phonetics and linguistics, as it helps speakers and learners identify and produce different vowel sounds.