ANS:D - All the above.

1. Flourish in the presence of free oxygen: Aerobic bacteria require oxygen to carry out their metabolic processes. They thrive in environments where oxygen is readily available.
2. Consume organic matter as their food: Aerobic bacteria utilize organic matter as a source of food. They break down complex organic compounds into simpler forms through aerobic respiration, releasing energy in the process.
3. Oxidize organic matter in sewage: Aerobic bacteria play a crucial role in the biological treatment of sewage. They oxidize and decompose organic matter present in sewage, helping to break down pollutants and reduce the organic content of wastewater.