Which of the following steps in Fig 3 involves plants releasing water vapor back into the atmosphere? evaporation
transpiration
condensation
runoff

Plants release water vapor into the atmosphere through the process of transpiration.

Explanation:

The water cycle is a cycle that goes through all of Earth's spheres. One of those spheres is the biosphere, and the main 'player' there are the plants. The plants use water in order to be able to survive and do their internal processes, but they also release the surplus of water. The surplus of water is released through the process of transpiration.

The process of transpiration basically is a process where the plants release water vapor into the atmosphere through their pores. By doing so, the plants release the excess water from them, while also contributing to an increase of water vapor in the atmosphere, thus making the climate cooler and increasing the amounts of precipitation when that water comes in a situation to condensate.