Plants could serve several functions on space vehicles. One obvious use is to provide
fresh food. Fresh fruits and vegetables are a welcome change from prepackaged,
freeze-dried foods. Also, plants could help to recycle wastes. They can take up carbon
dioxide released by humans and release oxygen back into the air. Finally, plants could
provide a psychological benefit by creating a pleasant natural space within the high-
technology environment.
Choose (a or b)
a. Addition
b. Time