What is X in the following conversion?

Options

1. A$\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}, \mathrm{H}_{2} \mathrm{SO}_{4} / \mathrm{H}_{2} \mathrm{O}$
2. B$\mathrm{HIO}_{4}$
3. C$\mathrm{PCC} / \mathrm{CH}_{2} \mathrm{Cl}_{2}$
4. D$\mathrm{OsO}_{4},\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C.COOH},\left(\mathrm{CH}_{3}\right)_{3} \mathrm{COH}, \mathrm{OH}^{-}$