Identify what the reactions imply

Compound $A$ has formula $C_4H_8$. This suggests one degree of unsaturation: $\text{DBE} = \frac{2C+2-H}{2} = \frac{2(4)+2-8}{2}=1$ So $A$ is either:

• an alkene, or
• a cycloalkane.

Use ozonolysis clue

Ozonolysis cleaves a carbon-carbon double bond to form carbonyl compounds. Since $A$ gives a product $B$ with formula $C_3H_6O$, $A$ must be an alkene, not a saturated cycloalkane.

So options B and D are eliminated.

Check option A: 2-Methylpropene

Structure: $CH_2=C(CH_3)_2$

On ozonolysis, cleavage of the double bond gives:

• formaldehyde, $HCHO$ from the terminal $CH_2$
• acetone, $(CH_3)_2CO$ from the substituted carbon

Acetone has formula: $C_3H_6O$ which matches compound $B$.

Also, oxidative cleavage with hot acidic $KMnO_4$ of 2-methylpropene gives acetone (along with further oxidation product from formaldehyde side), so formation of $B$ is consistent.

Check option C: But-2-ene

Structure: $CH_3-CH=CH-CH_3$

Ozonolysis gives two molecules of ethanal: $CH_3CHO$ whose formula is: $C_2H_4O$ This does not match $C_3H_6O$.

So option C is incorrect.

Conclusion

The only compound that gives a product $B$ with formula $C_3H_6O$ on both ozonolysis and oxidative cleavage is: $\boxed{\text{2-Methylpropene}}$

Compare with stored correct answer

Stored correct answer: A

Our derived answer: A

They match.