The correct order of increasing thermal stability of the given compounds is

I. HF

II. HBr

III. HCl

IV. HI

Statement I: Acid strength increases in the order given as

$\mathrm{HF}<<\mathrm{HCl}<<\mathrm{HBr}<<\mathrm{HI}$

Statement II:
As the size of the elements $\mathrm{F}, \mathrm{Cl}, \mathrm{Br}, \mathrm{I}$ increases down the group, the bond strength of $\mathrm{HF}, \mathrm{HCl}$ $\mathrm{HBr}$ and HI decreases and so the acid strength increases.

In the light of the above statements, choose the correct answer from the options given below.