I think this question is meant to be placed in the Geometry category. :)
Lava flows are the least hazardous of all processes in volcanic eruptions. How far a lava flow travels depends on the flows temperature, silica content, extrusion rate, and slope of the land. A cold lava flow will not travel far and neither will one that has a high silica content. Such a flow would have a high viscosity<span> (a high resistance to flow). A basalt flow like those in Hawai'i have low silica contents and low viscosities so they can flow long distances. Such a flow can move as far away as 4 km from its source and have a thickness of 10 m (Bryant, 1991). These flows can move at rates of several kilometers per hour (Scott, 1989). </span><span>More silica-rich flows can move as far away as 1.3 km from their sources and have thicknesses of 100 m (Bryant, 1991). These flows can move at rates of a few to hundreds of meters per hour (Scott, 1989). If a lava flow is channelized or travels underground in a lava tube then the distance it travels is greatly extended.</span>
Scientists believe that increased pollution may cause global warming because pollution includes greenhouse gases, which trap heat in the Earth’s atmosphere.
Option B
<u>Explanation</u>:
When the average temperature of earth increases and rises continuously above the normal value for a long period of time the it is referred as global warming.
Human beings are major cause in increasing pollution by various means whether its chemical industrial metallic or any other type of pollution. The major contributing factor in aiding pollution is the smoke from factories or vehicles which increases the carbon dioxide level above normal and when these gases rises they are trapped inside the earth surface and produce a green house effect. This is the main reason that scientists think aboutglobal warming.
