C

Step 1: Analyze the problem to find the required horizontal speed. The stuntman is making a projectile motion where he will jump horizontally off the roof and fall vertically due to gravity.

Step 2: The vertical distance fallen is 4.9 meters (height of the first building to the second). The time taken (t) to fall this height can be calculated using the formula for free fall:
$$ h = \frac{1}{2} g t^2 $$
Here, h is the height (4.9 m), and g is the acceleration due to gravity (approximately 9.8 m/s²). Rearranging gives:
$$ t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 \times 4.9}{9.8}} = \sqrt{1} = 1 ext{ second} $$

Step 3: To successfully land on the next building, the horizontal distance (6.2 m) must be covered in 1 second. The horizontal speed required can be found using:
$$ \text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{6.2 m}{1 s} = 6.2 ext{ m/s} $$

Conclusion: The minimum roof top speed required is 6.2 m/s. Therefore, the correct answer is option C.