In the water cycle, 'transpiration' is primarily performed by which group of living organisms?

Correct answer: By plants

Transpiration is the loss of water vapour from the aerial parts of plants, especially through tiny openings called stomata in leaves. Plants take up water from the soil through their roots. Much of that water moves upward through the plant, and some is released to the atmosphere through the stomata. This process connects plant life with the movement of water in the hydrological cycle and also contributes to cooling and water transport.

Option B is correct because plants are the main living organisms performing transpiration. Animals and microorganisms can release water vapour in other ways, but the biological process named transpiration specifically refers mainly to water loss from plants. The stomata regulate this loss by opening and closing. Thus the supplied answer correctly identifies plants, while the other groups are not the primary answer for this term.