Which interval named for its size spans seven semitones?

• A. Minor seventh
• B. Major second
• C. Augmented fourth
• D. Perfect fifth

Answer: (D)

Think of intervals by how many semitones (half steps) they contain. Spanning seven semitones corresponds to the size of a fifth above the root, and that size is called a perfect fifth. For example, going from C up to G covers seven half steps and is labeled a perfect fifth—the quality “perfect” signals a size that isn’t major or minor.

So seven semitones match the perfect fifth exactly. The other options don’t fit: a minor seventh is larger (ten semitones), a major second is much smaller (two semitones), and an augmented fourth is six semitones (the tritone), not seven.