1. Expansion joints in sidewalks and roads allow space for thermal expansion of concrete and asphalt.

What causes thermal expansion, and why do sidewalks have expansion joints to allow it?

The nature of photosynthesis is C) an energy-releasing proces. During photosynthesis, molecules are released that the plant will then feed upon to enable it to be able to grow. In this process, the form of energy produces comes with the substance glucose, which is necessary for further processes allowing the plant to grow and repair itself to take place.