In an experimental study on the effects of sleep deprivation on depression, the number of hours that a participant stays awake is represented by the
a. random variable. b. independent variable. c. dependent variable. d. control variable.

The number of hours a participant stays awake is the independent variable of the study. This study would require the amount of sleep to be controlled and changed by the experimenters in order to view the changes in effects. This is the definition of an independent variable.

not  

cuba  

russia  

iraq  

el salvador  

explanation:

known as the land of volcanoes, el salvador has visit seismic tremors and volcanic movement. it is the main nation in central america that does not have a coastline on the caribbean sea. about portion of all salvadorans live in the wide open. they are poor and don't have power or running water in their homes. in 1525, pedro de alvarado, a lieutenant of cortés's, vanquished el salvador. el salvador, with alternate nations of central america, pronounced its freedom from spain on sept. 15, 1821, and was a piece of a league of central american states until the point when that association broke up in 1838.