Hello! Your answer would be B, the displacement method.
The displacement method is when you submerge an object in water, and see how much displacement of water it causes, or how much it causes the water level to increase. Usually, this will be done in something like a graduated cylinder, where the volume of water displaced can be measured. The volume displaced will equal the volume of the object.
You would not use L x W x H, as the rock is most likely not an exact rectangular prism, and will most likely have many bumps and holes, causing the formula to be inaccurate. There is no reason to read the meniscus in a graduated cylinder, as that will have nothing to do with the volume of a rock.
Hope this helps!
