You have to push a heavy box across three surfaces: a grassy field , ice rink, and a concrete playground. Which surface will be easiest to push the box across and WHY ?

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space.b. we'll know it immediately because it will be brighter than the full moon in the sky.c. we won't know about it until 600 years from now.d. none of the above.