Need help on to answering this with explanation please so I can then understand the topic, thank you Please answer only letters C,D and letter E thank you

1. Show the repeating unit which would be obtained in the polymerization of: H H (a) H,C-C-CH-CH (b) CH-C-CN CH NCO (c) (d) (e) NCO + HNCH,CH,NH, H-C C-H and O=C H HOCH,CH,OH and COOH