Read the following passage and mark the letter A, B, C, or D to indicate the correct word or phrase that best fits each of the numbered blanks.

The string family is the largest (15)____ of the orchestra. The four main stringed instruments look similar but are all different sizes. Each can be played by plucking the strings with the fingers or with a bow, which is pulled (16)____ across the instrument's four strings.

The VIOLIN is the smallest of the string instruments and can play the highest (17)____. The violin often plays the melody - this is the tune you will be humming after you leave (18)____ performance.

The VIOLA is slightly larger than the violin. Because it is bigger, it can play lower notes. (19)____ the viola is only a little bit bigger than the violin, it can be hard to tell them (20)____. The viola plays many beautiful melodies just like the violin.

Choose the best answer to fill in the blank (15)