Which of the following statements about methanogens is not correct?

Statement (c) is incorrect. Correct information about the statement is as follows Certain bacteria, which grow anaerobically on cellulosic material, produce large amount of methane along with $\mathrm{CO}_2$ and $\mathrm{H}_2$. These bacteria are collectively called methanogens and one such example is Methanobacterium. Rest statements are correct.