Rank the following groups in order of decreasing priority

[Dhanalakshmi]

Rank the following groups in order of decreasing priority.

a. −COOH,−H,−NH₂,−OH
b.−H,−CH₃,−Cl,−CH₂Cl
c.−CH₂CH₃,−CH₃,−H,−CH(CH₃)₂
d.−CH=CH₂,−CH₃,−C≡CH,−H