What technological breakthrough event did Brahms take part in?

Explanation:

Nineteenth-century organ music was driven by two overarching achievements: the technological breakthroughs that allowed for greatly expanded, and colorfully diverse, instruments; and a rediscovery of the repertoire from the baroque period, especially the works of Johann Sebastian Bach. Large organs with expanded ranges and tonal palettes enabled composers like Liszt to write complex and virtuosic symphonic pieces. Brahms eschewed the grandiose by producing a small yet highly personalized group of works that exhibit the composer's debt to Bach and the baroque revival of the early nineteenth century.

(a) i got it right on the test