#### Solution By Steps

***Step 1: Symphonies***

Debussy did not create masterpieces in the genre of symphonies. He only composed one symphonic work, "La Mer," which is more of a symphonic suite than a traditional symphony.

***Step 2: Chamber music***

Debussy did create masterpieces in the genre of chamber music. Notable works include his String Quartet in G minor and Sonata for Flute, Viola, and Harp.

***Step 3: Art songs***

Debussy did create masterpieces in the genre of art songs. His song cycle "Ariettes oubliées" and "Fêtes galantes" are well-regarded examples.

***Step 4: Piano music***

Debussy did create masterpieces in the genre of piano music. His "Clair de Lune" and "Preludes" are iconic pieces in the piano repertoire.

#### Final Answer

Debussy did not create masterpieces in the genre of Symphonies.

#### Key Concept

Debussy's Musical Genres

#### Key Concept Explanation

Debussy excelled in various genres like chamber music, art songs, and piano music but did not create masterpieces in the genre of symphonies.