$$ \text { Consider the following three resonance structures } $$

The correct order of their stabilities is

From the following compounds, the ones which contain both $s p$ and $s p^2$ hybridised carbons are

Among the compounds

(i) $\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{COOH}$

(ii) $\mathrm{CH}_2=\mathrm{CH}-\mathrm{COOH}$

(iii) $\mathrm{CH}_3-\mathrm{CH}_2 \mathrm{COOH}$ and

(iv) $\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OH}$

The correct order of acid strength is