Answer: B) Gradually Explanation: All of us, believe that the Solar System evolved from a giant cloud of dust and gas. They believe that this dust and gas began to collapse under the weight of its own gravity. As it did so, the matter contained within this could begin moving in a giant circle, much like the water in a drain moves around the center of the drain in a circle. At the center of this spinning cloud, a small star began to form. This star grew larger and larger as it collected more and more of the dust and gas that collapsed into it. Further away from the center of this mass where the star was forming, there were smaller clumps of dust and gas that were also collapsing. The star in the center eventually ignited forming our Sun, while the smaller clumps became the planets, minor planets, moons, comets, and asteroids.

Answer: A) The most commonly thought of hazard in construction. This hazard includes radiation, extreme temperatures, noise, and vibration. Explanation: A physical hazard is defined as "A factor within the environment that can harm the body without necessarily touching it." Vibration and noise are examples of physical hazards.   Physical hazards include but aren't limited to electricity, radiation, pressure, noise, heights and vibration amongst many others.

Answer: D) nutrients and other life-sustaining molecules are in limited supply and must be continually recycled Explanation: Biogeochemical cycles are crucial to ecosystem function because ::   1. Chemical elements are available in only limited amounts and must be recycled. 2. Nutrients and other life-sustaining molecules are in limited supply and must be continually recycled.