A

Step 1: Calculate the weight (gravitational force) acting on the body:
Weight (W) = mass \times g = 72 \text{ kg} \times 10 \text{ m/s}^2 = 720 \text{ N}.

Step 2: Calculate the net force acting on the body:
Since the body is lifted with an acceleration of \frac{g}{10} = 1 \text{ m/s}^2, the net force (F_net) can be calculated as:
F_net = mass \times acceleration = 72 \text{ kg} \times 1 \text{ m/s}^2 = 72 \text{ N}.

Step 3: Calculate the actual force exerted by the string (Tension):
Using the equation:
F_net = T - W \\=> T = F_net + W = 72 \text{ N} + 720 \text{ N} = 792 \text{ N}.

Step 4: Calculate the work done by the tension in the string (W1):
W1 = Tension \times Distance = 792 \text{ N} \times 15 \text{ m} = 11880 \text{ J}.

Step 5: Calculate the work done by gravitational force (W2):
W2 = -W \times Distance = -720 \text{ N} \times 15 \text{ m} = -10800 \text{ J}.

Step 6: Calculate the kinetic energy (K):
K = W1 + W2 = 11880 \text{ J} - 10800 \text{ J} = 1080 \text{ J}.

Step 7: Calculate the final speed (v):
K = \frac{1}{2} mv^2 \text{ => } v = \sqrt{\frac{2K}{m}} = \sqrt{\frac{2 \times 1080}{72}} = \sqrt{30} \approx 5.47 \text{ m/s}.

Therefore, the correct answer for W1 is [A] 10800 J, thus the correct option is A.