Which of the following is a non-symbiotic biofertilizer?

[HDquiz quiz = "1966"]

Non-symbiotic nitrogen-fixing bacteria are nitrogen-fixing bacteria that are free-living soil bacteria and are not directly associated with plants. These bacteria fix nitrogen from the atmosphere and provide it to the crop plants. Examples of free-living non-symbiotic nitrogen-fixing bacteria are Azotobacter, Azospirillum, etc.