A body of granite was found to underlie sandstone. pieces of sandstone were found in the granite. which is younger, the granite or the sandstone, and which principle of relative age determination supports your conclusion

It is obvious that the sandstone is older than the granite. This is because the sandstone had to already exist when the granite formed from molten rock, as some of the sandstone was captured within the layer of hardening granite. The geological principle of inclusions supports this conclusion. Inclusions, in this case the sandstone, are always older than the rock they are found in.