Convection currents in air and water occur because warm fluids are less...
Option (a) is the correct answer.
A process in which a fluid (liquid or gas) whose cooler material (more dense) sinks at the bottom and warm material (less dense) rises at the top is known as convection process.
This intermixing of materials leads to the development of convectional currents.
Therefore, we can conclude that convection currents in air and water occur because warm fluids are less dense than cold fluids.
warm fluids are less dense than cold fluids