The high silica content in grasses and the thick enamel layer on horse teeth are examples of: 1. a symbiotic relationship. 2. the "escape and radiate" hypothesis. 3. co-evolution. 4. a trade-off between growth and defense.

The steps in the formation of extrusive igneous rocks are listed below in an incorrect order: 1. rock melts due to high temperature. 2. rock is buried deep under earth's surface. 3. magma is forced out of earth's surface during volcanic eruption. 4. lava cools and crystallizes to igneous rock. which of these best shows the correct order of steps in the formation of extrusive igneous rocks? 1, 3, 4, 2 2, 1, 3, 4 3, 4, 2, 1 4, 2, 1, 3