Chemosynthetic bacteria are those bacteria

The correct option is B Which synthesize food without light

• Chemosynthetic bacteria are organisms which obtain energy from the oxidation of inorganic molecule. They do not require light. Inorganic molecules act as a source of energy and get converted into organic substances.
• Inorganic molecules, such as ammonia, molecular hydrogen, sulphur, hydrogen sulphide and ferrous iron, are used to produce the organic compounds needed by the bacteria for their subsistence.
• For example, Nitrifying bacteria is a chemosynthetic bacteria which obtain energy from the oxidation of inorganic molecule like ammonia into organic molecules like nitrites and then to nitrates by the process of biological oxidation

So, the correct answer is option B.