7. which one of the following is the main reason why the earth has seasons? (a) earth's orbit is elliptical. we have summer when we are closer to the sun and winter when we are farther from the sun. (b) the tilt of earth's axis of rotation causes one hemisphere of the planet to be substantially closer to the sun during the day than the other hemisphere. because it is closer to the sun, it receives more solar energy per hour. (c) over the course of the year, the tilt of earth's axis varies from 23.5° to 0° in such a way as to bring more heating per hour in the summer than in the winter. (d) the tilt of earth's axis of rotation causes the sun to pass higher in the sky during the day in one hemisphere than in the other, thereby giving more daylight hours and more heating per hour. (e) it has seasons so that sunbathers will know when to go to the beach, and skiers will know when to go skiing.

Scientist: cross-sections of stalactites—calcite formations deposited on cave ceilings by seeping water—can reveal annual variations in rainfall in particular areas over hundreds and thousands of years. we often found that when—according to these cross-sections—drought occurred in a particular area, it coincided with the collapse of an ancient society in that area. i hypothesize that drought reduced agricultural productivity in these areas, thereby leaving these societies without the resources needed to handle internal stresses and external threats. which of the following, if true, would most weaken the support for the scientist's hypothesis? a. many droughts indicated in the cross-sections of stalactites do not correspond with the collapse of a society in that area. b. information from the cross-sections of stalactites alone cannot reveal the level of agricultural output in an area at a particular time. c. most of the societies that collapsed during droughts did so when internal power struggles coincided with military raids from neighboring societies. d. most of the societies that collapsed during droughts maintained large stockpiles of food and water at the time of their collapse. e. information from stalactites also suggests that the collapse of some societies coincided with periods of abnormally high rainfall.

Which of the following statements about the us federal boundaries is true

How did mercantilist policies european countries build wealth and power