JEE Main 2020 — Electrostatics Question with Solution

Two identical electric point dipoles have dipole have dipole moments ${\overrightarrow{\mathrm{p}}}_1=\mathrm{p}\hat{\mathrm{i}}$ and ${\overrightarrow{\mathrm{p}}}_2=-\mathrm{p}\hat{\mathrm{i}}$ and are held on the $\mathrm{x}$-axis at distance '$\mathrm{a}$' from each other. When released, they move along the $\mathrm{x}$-axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is '$\mathrm{m}$', their speed when they are infinitely far apart is :