Which of the following composers is known for their nationalist music from Russia?

Mussorgsky is recognized for his significant contributions to nationalist music in Russia, a characteristic reflected in his compositions that draw from Russian folklore, history, and culture. His famous works, such as "Pictures at an Exhibition" and "Boris Godunov," highlight the influence of Russian themes and settings, showcasing a distinctively nationalistic approach in music that prioritizes the Russian identity during a time when composers were embracing their national heritage.

The other composers, while undoubtedly influential in their own right, do not embody the same Russian nationalist spirit. Janáček, for instance, is celebrated for Czech nationalism, focusing on the folk traditions of his homeland rather than Russian music. Dvořák, meanwhile, is known for his contributions to Czech national music but does not delve into Russian themes. Similarly, Fauré, a French composer, tends to embody the styles and aesthetics of French music rather than any form of Russian nationalism.