Identify `(A)` to `(D)`.

Explanation

`D.U.`in `A=((2n_(C)+2)-n_(H))/(2)=((2xx7+2)-10)/(2)=3^(@)`
`D.U. `in `A=3^(@)(1^(@)implies` Ring `),[`Two`(-COOH)` groups`]=2^(@) `
`D.U. `in `A=2^(@)`
Procedd reverse from `(B):`

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