Given below are two statements (A-B) each with one or more blanks. Select the option which correctly fills the blanks in the statements -
Statements :
A. Microbes consume the major part of the organic matter in the effluent and reduce ......................of sewage.
B. Certain bacteria which grow anaerobically on cellulosic material, produce large amount of methane along with `CO_2 and H_2.` The bacteria are commonly called as .....................and one such common bacterium is.....................

Options

A. `A-CO_2` demand, B-methanogens, Methanobacterium
B. A -Carbon, B-methanogens, Methanobacterium
C. A-biochemical oxygen demand, B-methanogens, Methanobacterium
D. A-biochemical oxygen demand, B - Methylokorus infernorum

Answer

To solve the given statements, we need to fill in the blanks correctly based on our understanding of microbes and their role in sewage treatment and methane production.

### Step-by-Step Solution:

1. **Understanding Statement A**:
- The first part of Statement A mentions that "Microbes consume the major part of the organic matter in the effluent and reduce...".
- In sewage treatment, microbes break down organic matter, which leads to a reduction in the **"BOD" (Biochemical Oxygen Demand)** of sewage. BOD is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water.

**Fill in the blank**: BOD

2. **Understanding Statement B**:
- The second part of Statement B states, "Certain bacteria which grow anaerobically on cellulosic material, produce large amounts of methane along with CO2 and H2."
- The bacteria that perform this function are commonly referred to as **"methanogens"**. They thrive in anaerobic conditions and are crucial in the breakdown of organic materials, especially cellulose.

**Fill in the first blank**: methanogens

3. **Identifying a Common Bacterium**:
- The statement continues with, "and one such common bacterium is...". A well-known example of a methanogen is **"Methanobacterium"**. This genus includes several species that are involved in methane production.

**Fill in the second blank**: Methanobacterium

### Final Answers:
- **Statement A**: Microbes consume the major part of the organic matter in the effluent and reduce **BOD** of sewage.
- **Statement B**: Certain bacteria which grow anaerobically on cellulosic material produce large amounts of methane along with CO2 and H2. The bacteria are commonly called as **methanogens** and one such common bacterium is **Methanobacterium**.