B

Step 1: Identify the force acting on the body from the graph. For the first 25 m, the force is constant at 10 N.
Step 2: Use Newton's second law, which states that Force = mass \( \times \) acceleration (F = ma). Here, m = 5 kg and F = 10 N.
Therefore, acceleration (a) = \( \frac{F}{m} = \frac{10 \text{ N}}{5 \text{ kg}} = 2 \text{ m/s}^2 \).
Step 3: Apply the kinematic equation for motion starting from rest: \( v^2 = u^2 + 2as \), where u = initial velocity (0 m/s), a = acceleration (2 m/s²), and s = distance covered (25 m).
Plugging in the values gives: \( v^2 = 0 + 2 \times 2 \times 25 = 100 \).
Step 4: Taking the square root: \( v = \sqrt{100} = 10 \text{ m/s} \).
Therefore, the speed of the body when it has covered 25 m is 10 m/s.