The air begins to rise into the atmosphere. When air rises, it cools down and condenses into precipitation and clouds. This is why an approaching low pressure system means an increased chance for clouds, rain, or snow. It is called "low pressure" because as air rises, the air pressure is lower at the surface.
Answer: A. cooled and hardened lava from volcanoes
C. sediments deposited by rivers and ocean currents
An accretion is a process in which new materials are added to a tectonic plate or landmass. This process causes the enlargement of the landmass. The materials being added includes sediments, lava from volcanic eruptions and other materials from other sources.
The process of accretion can enlarge the size of a continent along its edge. The new land comes from the cooled and hardened lava from volcanoes and other reason is sediments deposited by rivers and ocean currents.