What does sand grab onto to form beaches? bedrock seaweed mollusk shells cracks and fissures in rock

The correct option is option a bedrock.

Explanation- The sand present on the beaches has to stay there and stick to something to form ground.  This ground is the Bedrock present at the beaches which offer a solid grounding over which the sand is held on to.  

If this Bedrock would not have been present and would have some must completely or it would have been really difficult to stand as standing on it would have led to submerging of legs into the sand.  

smooth muscle is composed of involuntary muscles found within the walls of organs and structures such as the esophagus, stomach, intestines, and blood vessels. those muscles push materials like food or blood through organs. unlike skeletal muscle, smooth muscle can never be under your control.