How do scientists know that dark matter exists? A) It’s heat raises the temperature of space.

B) Its gravity affects objects around it.

C) It gives off electromagnetic waves.

D) All of these.

Match the mountains with the type of collision that formed them. a. andes b. aleutians c. north american cordillera d. appalachians 1. continental- continental 2. continental- oceanic 3. oceanic- oceanic 4. arc- continent