Two blocks, A and B, with masses 10 kg and 15 kg respectively, are placed side-by-side on a horizontal surface. A horizontal force of 200 N is applied to block A. The coefficient of friction between t

Mass of block A, $m_A = 10 \text{ kg}$
Mass of block B, $m_B = 15 \text{ kg}$
Applied horizontal force, $F_{applied} = 200 \text{ N}$
Coefficient of friction between the blocks and the surface, $\mu = 0.2$
Acceleration due to gravity, $g = 10 \text{ m/s}^2$

Since the blocks are in contact and move together, we can treat them as a single system.
Total mass, $M = m_A + m_B$

The normal force ($N$) acting on the system is equal to its total weight.

The friction force ($f_{friction}$) opposing the motion is given by $\mu N$.

The net force ($F_{net}$) is the applied force minus the friction force.

Using Newton's second law, $F_{net} = M \times a$, where $a$ is the acceleration of the system.

The acceleration of the system is $6 \text{ m/s}^2$. This matches option (b).

The final answer is $\text{(b)}$.