The correct answer is: $\sqrt{6gm\lambda}$
Explanation
You have a square root over the product $2g\lambda\cdot3m$. Multiply the numeric factors $2$ and $3$ to get $6$, then combine the remaining symbols under the radical.
Steps:
- $$2\times3=6$$
- $$\sqrt{2g\lambda\cdot3m}=\sqrt{6gm\lambda}$$
Therefore the expression simplifies to $\sqrt{6gm\lambda}$.