An idea that the universe originated with an explosion is supported by repeated observations of light from distant galaxies traveling away from Earth. An idea that has been tested repeatedly and is supported by repeated results is MOST likely a

the answer is a or when it says crossing over

lizards have adapted to life in the desert. some desert lizards have toes with spiny scales to them run across the sand without sinking. some use the sand to hide from predators, or to search for small animals that they prey upon.

the answer is c. it will give up it's valence electron to the other atom.