Gordon finds a rock in the park. it contains a small fossil. gordon has most likely found pumice gneiss sandstone granite

Gordon has most likely found sandstone. Fossils, which are imprints of dead organisms, primarily form in sedimentary rocks, which are one of the three main types of rocks. Among the choices, only sandstone is a type of sedimentary rock. Gneiss is a metamorphic rock. Granite and  pumice are igneous rocks.

By studying his thoughts

He could think something but not show it in any way, therefore thoughts