Answer: Option (b) is the correct answer.
Step-by-step explanation:
When we say that an equation is balanced then it means there are equal number of atoms on both reactant and product side.
For example,

Number of atoms on reactant side are as follows.
= 2
= 1
Number of atoms on product side are as follows.
= 1
= 1
Therefore, to balance this equation we multiply
by 3 on reactant side and multiply
by 3 and
by 2 on product side.
Hence, the balanced equation will be as follows.
