$A$ polymer $X$ is biodegradable and is obtained from the monomers $Y$ and $Z$. What are $Y$ and $Z$?

• A
  $H_2N-CH_2-CH_2-COOH$ and $H_2N-(CH_2)_5-COOH$
• B
  $H_2N-CH(CH_3)-COOH$ and $H_2N-(CH_2)_5-COOH$
• C
  $CH_3-CH(OH)-CH_2-COOH$ and $CH_3-CH_2-CH(OH)-CH_2-COOH$
• D
  $HO-CH(CH_3)-CH_2-COOH$ and $HO-CH(CH_2CH_3)-CH_2-COOH$