Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods

Texas has an impending storm, and california is experiencing a water crisis. match the technologies with the state that can use them to reduce the effects eddies natural hazards. texas is the storm cellar and the wood that is crisscrossed. california is the dam and the storage tanks

Ialready know the answers to these questions and they are on the attachment. but i just need to know why that answer is the correct one. plz asap! this is for a report that i need to email by 10!

Which is not true about balanced forces?