In moist climates, tends to dissolve limestone near the surface, resulting in cave formation.

I believe the correct word to fill in the blank is water. In moist climates, water tends to dissolve limestone near the surface, resulting in cave formation since limestone is soluble to water. Hope this answers the question. Have a nice day.

Answer (datum point);

In a right-angled triangle: 1- the hypotenuse is the longest side2- we can apply pythagorean rule which states that: (hypotenuse)^2 = (side1)^2 + (side2)^2for the given triangle,longest side is 15 cm  side1 = 9 cmside2 is 12 cm  to check whether the triangle is right-angled or not,compare (15)^2 to the summation of (9)^2 and (12)^in other words, compare 225 to the summation of 81 and 144if they are both equal, then the triangle is right-angles, otherwise, it is not.you haven't provided the diagram showing her work, so i cannot tell the choice. however, apply my explanation to the question you have.