Which of the following rocks has the highest porosity?

A) a fine-grained shale
B) lightly cemented sandstone
C) a coarsely crystalline granite
D) a metamorphic schist or gneiss

Lightly cemented sandstone typically has higher porosity compared to fine-grained shale, coarsely crystalline granite, and metamorphic rocks like schist or gneiss. This is because the spaces between the sand grains can remain relatively open and less filled with cementing material, allowing for more void spaces where fluids can reside.