Concept:
Sawdust is a lignocellulosic plant material. It contains cellulose and other organic compounds. On suitable chemical treatment, sawdust can be used for the manufacture of oxalic acid.
Oxalic acid is a dicarboxylic acid having two carboxylic acid groups.
Its structure is:
\[
HOOC-COOH
\]
Identification of options:
Option (A) shows:
\[
CH_3COOH
\]
This is acetic acid.
Option (B) shows:
\[
HOOC-COOH
\]
This is oxalic acid.
Option (C) shows a tricarboxylic acid structure, which corresponds to citric acid.
Option (D) shows a higher chain carboxylic acid structure.
Now, the acid manufactured using sawdust is oxalic acid.
Since option (B) represents oxalic acid, the correct answer is:
\[
\boxed{(B)}
\]
