Where do rivers usually begin?

at the ocean
at groundwater outlets
in mountainous regions
in lakes and larger rivers

Asnail, elodea (aquatic plant), or both were added to the tubes and they were stoppered. tubes were placed under a grow light for 24 hours and the results recorded. the test tubes were then covered for 24 hours to produce a dark environment and the results recorded. which statement best explains the change in test tube d from the light setup to the dark setup.

Efficiency is the percent of work put into a machine by the user (input work) that becomes work done by the machine (output work)

Organisms are classified, or grouped into categories, based on similarities in their characteristics and/or evolutionary relationships. the study of how organisms are classified is known as