Compound K displayed a strong band at 1680 cm−1 in its IR spectrum. Its 1H-NMR spectral data are as follows:
δ (ppm):
7.30 (d, J = 7.2 Hz, 2H)
6.80 (d, J = 7.2 Hz, 2H)
3.80 (septet, J = 7.0 Hz, 1H)
2.20 (s, 3H)
1.90 (d, J = 7.0 Hz, 6H)
The correct structure of compound K is:





\[ \boxed{\text{Correct structure of K is given in option (C)}} \]
