Is Schubert's Death and the Maiden a quartet or an art song?

Schubert’s representative works 1. Representative works (1) The most famous vocal works: "The Devil", "Wild Rose", "Trout", "The Wanderer", "Serenade", "Lullaby", "Ave Maria" and the vocal suites "The Beautiful Mill Girl", "Winter Journey" and " "Swan Song" (2) Chamber music: ""Trout" Piano Quintet" ""Death and the Maiden" String Quartet in D minor" (3) Piano music: "Wanderer's Fantasia", "Improvisation" and "Musical Moments" "(4) Symphony: "Eighth Symphony" ""Unfinished" Symphony" = "Ninth Symphony" 2. Art Song (Lied) (1) Origin: The term art song was used before the 13th century. In the 16th century, German and Austrian composers combined the polyphonic techniques of the Flemish school with German solo songs since the Middle Ages to form a four-part secular vocal genre - Lied. However, in the subsequent development of the term art song, it especially refers to the German art songs of the Romantic period from the late 18th to the early 19th century. . (2) Meaning: Art songs are songs composed by composers with poems as lyrics and based on the content of the poems. In art songs, music and poetry are organically combined, usually in two forms: dramatic and lyrical, written in sections and through sections, and accompanied by accompaniment. The accompaniment of art songs occupies an important position in the song, and is responsible for content that cannot be expressed by the singing melody. Many accompaniments even have solo value. (3) Representative figures: composers Schubert, Schumann, Brahms, Wolf, Mahler and Richard Strauss, etc.; lyricists Goethe, Eisendorf, Heine, Schiller, etc. wait. 3. Artistic achievements (1) In terms of artistic songs, he made important contributions and created a number of artistic songs with epoch-making influence. (2) In terms of symphony, the work completely expresses the contradiction between ideal and reality. Inspired by Schubert's break with the four-movement structural pattern of the classical symphony, people began to break away from the constraints of their predecessors and entered a new world of romantic symphony development. (3) In terms of piano music and chamber music, Schubert's creation exudes the romantic characteristics reflected in his art songs. (4) He is a model of free musicians who makes a living by playing and publishing works. He is one of the first musicians to emerge from the bottom of society.