To answer this question you need some way to tell the ratio of ethylene glycol to the total original solution.

Statement 1:

This only gives the volume of the new solution and gives no information related to the ratio of ethylene glycol to total solution in the original solution.

Insufficient.

Statement 2:

This tells us the following.

The new solution is 60% ethylene glycol. Since there are 10 liters of new solution, there must be 6 liters of ethylene glycol in the new solution and 4 liters of water in the solution.

If there are 6 liters of ethylene glycol in the new solution and none has been added or removed, there were 6 liters of ethylene glycol in the original solution as well.

40% of the water has evaporated, leaving 4 liters of water. From this we could calculate the quantity of water in the original solution.

So we know how much ethylene glycol was in the original solution and we could, but we won't, calculate the quantity of water in the original solution.

Therefore, we could calculate the percentage of ethylene glycol in the original solution.

Sufficient.

The correct answer is B.