NTSE Stage 2 MAT 2017 Question Paper

According to the question
Average age of A, B and C is
$\frac{\mathrm{A}+\mathrm{B}+\mathrm{C}}{3}=4$
∴ $\mathrm{A}+\mathrm{B}+\mathrm{C}=129$
Now $\mathrm{C}=65$
∴ $\mathrm{A}+\mathrm{B}=64$
Since sum of ages of $\mathrm{A}+\mathrm{B}$ is less than age of C, therefore statement I alone is sufficient.