Answer:
2 feet trochee.
Step-by-step explanation:
According to the Poetry Foundation: "A foot usually contains one stressed syllable and at least one unstressed syllable". So, since we have 5 syllables in "music theory", we cannot have more than 2 feet. Considering that the kind of feet depends on the first syllable being unstressed (trochee) or stressed (iamb), and the fact that the word "Music" starts with a stressed syllableit seems that we have a 2 feet trochee.