Which of the following behaviors allows a bird to maintain a constant body temperature in extremely hot weather?
a. spreading wings
c. flattening feathers
b. panting
d. all of the above
user: bird bones are adapted for flight because they
a. are dense
c. are hollow
b. contain bone marrow
d. are longer than the bones of most animals

Aremote community desperately needs more electrical energy. it is located in an area with the following characteristics: average wind speed of 15 – 20 km/hr some medium-sized rivers with slow-moving currents few coal deposits some oil exploration being conducted within 400 miles based on the above information, which energy source would be the most economical and safest for the community to pursue? a. fossil fuel b. hydroelectric c. nuclear d. wind