Terylene polymer is obtained by condensation of

Terylene (also known as Dacron or PET — Polyethylene terephthalate) is a polyester polymer.

It is formed by the condensation polymerization of:

• Ethane-1,2-diol (ethylene glycol, $$HOCH_2CH_2OH$$)
• Benzene-1,4-dicarboxylic acid (terephthalic acid, $$HOOCC_6H_4COOH$$)

The reaction proceeds as:

$$nHOCH_2CH_2OH + nHOOC-C_6H_4-COOH \to [-OCH_2CH_2OOC-C_6H_4-CO-]_n + 2nH_2O$$

The ester linkage ($$-COO-$$) is formed between the $$-OH$$ groups of the diol and the $$-COOH$$ groups of the dicarboxylic acid, with the elimination of water.

Key point: The dicarboxylic acid must be the para isomer (benzene-1,4-dicarboxylic acid), not the ortho (1,2) or meta (1,3) isomer, to form the linear polymer chain characteristic of terylene.

Therefore, the correct answer is Option C.