Final answer:
The correct apparatus for determining the volume of a small block of unknown material is a measuring cylinder and a metre rule, as one can measure the block's dimensions or use the displacement method.
Step-by-step explanation:
Among the given options for determining the volume of a small block of unknown material, the only apparatus that would be appropriate are a measuring cylinder and a metre rule. When measuring the volume of regular solids, one can calculate it using the geometric formula for volume, which for a rectangle, is length x width x height, and for a cube, it is the edge length cubed. Since we are looking to determine the volume of a small block, assuming it is a regular solid, we would use the metre rule to measure its dimensions and compute the volume. Moreover, if the block is small enough and irregular, it could be submerged in water in a measuring cylinder to directly measure the volume of water displaced, known as the displacement method, which gives the volume of the block.