Ⅲ. An unknown compound (A), C₄H₇ClO₂, gave the following proton NMR data:(4%) 

(a)triplet, at 1.31 ppm (3H) 

(b)singlet, at 3.95 ppm (2H) 

(c)quartet, at 4.20 ppm (2H) 

Propose a structure for A.

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