Step 1: Identifying the Biodegradable Polymer Components.
Biodegradable polymers are those that can be broken down by microorganisms into natural substances such as water and carbon dioxide.

Step 2: Recognizing Monomers.
- A well-known biodegradable polymer is Polyhydroxyalkanoates (PHAs), which are derived from hydroxy acids.
- The monomers given in option (4) contain hydroxyl (-OH) and carboxyl (-COOH) functional groups, making them ideal candidates for forming biodegradable polymers.
- Other options include amino acids and linear dicarboxylic acids, which are less commonly used in biodegradable polymer formation.

Step 3: Conclusion. Since hydroxy acids serve as monomers for biodegradable polymers like polyhydroxybutyrate (PHB), option (4) is the correct choice.

Step 1: Understanding PHBV PHBV (Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) is a biodegradable polymer synthesized from two monomers: - -hydroxybutanoic acid ( )
- -hydroxypentanoic acid ( )

Step 2: Identifying the Correct Answer Since option (2) correctly matches these monomers, it is the right answer.

The reaction sequence shown is for Bakelite synthesis, which is a cross-linked polymer. The initial reaction involves the condensation of formaldehyde (HCHO) with phenol, followed by polymerisation under heat. This results in a three-dimensional network, characteristic of Bakelite, which is a cross-linked polymer.