Earth's tectonic activity is a significant factor that to sustain life on earth because the movement of earth's crustal plates affects volcanic activity and the atmosphere

True

Explanation:

Tectonic activities helps to keep the earth dynamic and constant changing. The dynamic earth is very important to sustenance of life on earth. Moving plates produces volcanic activities that bring new materials to the surface of the earth.These new materials through weathering produce fertile and rich soils for plants to grow. Also, gases from deep within the earth reaches the surface as a result of tectonic activities. These gases have been believed to have contributed to the origin of life on earth when it was still in a primitive phase.

81 is a composite number.