The idea of epicycles was introduced by which astronomer as an attempt to explain the retrograde motion of the planets in the geocentric universe model?
a. brahe
b. galileo
c. ptolemy
d. copernicus

basic principles: federalism, separation of powers, checks and balances, judicial review, representative democracy, limited government, rule of law, individual rights and responsibilities, consent of the governed, majority rule, popular sovereignty, equal protection.

d) in the state of iowa