During the Cambrian period, 600 mya, Georgia was part of the ocean floor. In fact, most of North America except Canada was under water. Evidence of this includes the presence of _____________________ rock as far as North Georgia, containing the fossils of marine organisms that had shells. The minerals in these rocks precipitated out of the seawater and combined with the shells of the organisms to form deposits.

A) basalt
B) granite
C) limestone ***********
D) sandstone

Yes, limestone.

The correct answer is C) limestone.

To arrive at this answer, we need to consider the information provided in the question. It states that during the Cambrian period, Georgia was part of the ocean floor along with most of North America (excluding Canada). Additionally, it mentions the presence of rock in North Georgia that contains the fossils of marine organisms with shells.

Limestone is a type of sedimentary rock that forms from the accumulation of the remains of marine organisms such as shells, coral, and other calcium-rich materials. It often forms in marine environments, making it a suitable match for the given context.

On the other hand, basalt is an igneous rock that forms from solidified lava or magma. While basalt can form in underwater volcanic eruptions, it does not directly link to the presence of marine organism fossils.

Granite is another type of igneous rock formed through the solidification of magma deep within the Earth's crust. It does not directly relate to the ocean floor or the formation of deposits containing marine fossils.

Sandstone is a sedimentary rock composed of sand-sized grains, often formed in terrestrial or shallow marine environments. While sandstone can contain fossils, it does not explicitly state the presence of marine organism fossils with shells in the question.

Thus, the presence of limestone in North Georgia, containing the fossils of marine organisms with shells, provides evidence that Georgia was part of the ocean floor during the Cambrian period.