Which of the following plays a role in the exchange of gases in plants?

Stomata are small pores found on the surface of plant leaves and stems that are involved in gas exchange between the plant's internal tissues and the air. They enable the uptake of CO2 for photosynthesis as well as the release of oxygen and other gases produced by the plant.

Palisade tissue, a type of mesophyll tissue found in leaves, is responsible for the majority of photosynthesis, but it has no direct role in gas exchange.

Sclerenchyma is a type of supportive tissue found in both plant stems and leaves that does not participate in gas exchange.

Mid-rib of a leaf is a structure that runs down the centre of the leaf and supports the blade. It does not participate in gas exchange, but it plays an important role in supporting the leaf and acting as a conduit for water, minerals, and nutrients to be transported from the stem to the rest of the leaf.