Lucasfilm produced The Mandalorian alongside Fairview Entertainment and Golem Creations. Lucasfilm is the Star Wars company responsible for developing and producing the series for Disney+.
Founded by George Lucas, Lucasfilm became the home of the Star Wars franchise and was acquired by The Walt Disney Company in 2012. Under Disney, Lucasfilm continued producing Star Wars films and expanded the franchise into streaming television, beginning with The Mandalorian in the live-action series format.
The other options belong to different entertainment companies or production ecosystems: Pixar is associated primarily with animated films, Bad Robot is J. J. Abrams’s production company, and Marvel Studios produces Marvel titles. Disney+ is the distributor and streaming platform here, not the production company named in the question.