Increasing basic properties of $\mathrm{T}\mathrm{i}{\mathrm{O}}_2,\mathrm{}\mathrm{Z}\mathrm{r}{\mathrm{O}}_2$ and $\mathrm{H}\mathrm{f}{\mathrm{O}}_2$ are in order:

• Correct answer
  A

  $\mathrm{T}\mathrm{i}{\mathrm{O}}_2<\mathrm{Z}\mathrm{r}{\mathrm{O}}_2<\mathrm{H}\mathrm{f}{\mathrm{O}}_2$
• B

  $\mathrm{H}\mathrm{f}{\mathrm{O}}_2<\mathrm{Z}\mathrm{r}{\mathrm{O}}_2<\mathrm{T}\mathrm{i}{\mathrm{O}}_2$
• C

  $\mathrm{H}\mathrm{f}{\mathrm{O}}_2<\mathrm{T}\mathrm{i}{\mathrm{O}}_2<\mathrm{Z}\mathrm{r}{\mathrm{O}}_2$
• D

  $\mathrm{Z}\mathrm{r}{\mathrm{O}}_2<\mathrm{T}\mathrm{i}{\mathrm{O}}_2<\mathrm{H}\mathrm{f}{\mathrm{O}}_2$

Hence, the correct answer is option: 'A'.