I dont understand this can you help me please.

Which describes the persian empire? choose all that are (a) the persian army defeated the athenians at the battle of marathon. (b) the persians avoided using ideas from the peoples they conquered. (c) cyrus allowed conquered peoples to keep their cultures. (d) darius i built a network of good roads for communication. choose all that are

Space is not completely empty. there are small particles in space. what happens when these particles come together?

The transcontinental railroad runs from the to the i. north ii. south iii. east iv. west a. i and ii b. ii and iii. c. iii and iv d. ii and iv