Which type of stress pattern is characterized by two consecutive syllables that are equally unstressed?

The correct answer is the type of stress pattern known as Pyrrhic. This pattern involves two consecutive syllables that are both unstressed, which means neither syllable carries an accent. This is relatively rare in English poetry, as most syllabic patterns tend to include at least one stressed syllable.

Understanding the characteristics of different metrical feet can clarify why Pyrrhic is the correct choice. Trochaic and dactylic feet both emphasize at least one syllable, whereby trochaic consists of a stressed syllable followed by an unstressed one, and dactylic features a stressed syllable followed by two unstressed syllables. Spondaic, on the other hand, includes two stressed syllables in succession. These definitions highlight that none of these other patterns correspond to the requirement of two equally unstressed syllables found in a Pyrrhic foot.