Question

what is one reason that exploring space is hard? it is very dangerous to drive on other planets. there are no stars outside our solar system. the speed of light cannot be measured. other galaxies are very far away from earth.

Explanation:

Space exploration is difficult due to vast distances. Other galaxies being far from Earth is a major obstacle. The first option about driving on other planets is not a main reason for general space - exploration difficulty. There are countless stars outside our solar system, so the second option is incorrect. The speed of light can be measured, making the third option false.

Answer:

D. Other galaxies are very far away from Earth.