Question

3. What adaptation of land plants helps it to control gas exchange with the atmosphere?

Answer 1

3) C. Stomata, as I explained in my previous answer.

4) B. Nonvascular, low-hanging plants living in moist environs don't have to fight gravity nearly as much as tall ones do. So they needn't highly developed vessels to transport to their tips

5) B. Gravity, see above. The higher trees/plants grew, the further their apical structures were from ground water sources, so the lignin-supported, strong vascular tissue (phloem) allows the transport of water against gravity, using a capillary method (benefiting from the adhesive effect of water molecules).