Bleaching powder, $\mathrm{Ca}(\mathrm{OCl})\mathrm{Cl}$, is treated with excess dilute $\mathrm{H}{}_2\mathrm{SO}{}_4$ and $\mathrm{Cl}{}_2$ is liberated. The oxidation states of the two chlorine atoms in bleaching powder and the type of redox change in forming $\mathrm{Cl}{}_2$ are

1. A$+1$ and $+1$; reduction only
2. B$-1$ and $-1$; oxidation only
3. C$+1$ and $-1$; disproportionation
4. D$+1$ and $-1$; comproportionation (both go to 0)