b. geyser -- 4. an eruption of hot water and steam
c. hot spring -- 2. ground water has come into contact with hot rocks and risen to the surface
d. travertine -- 3. massive deposits of calcium carbonate around a hot spring
Explanation:
A fumarole is opening of the crust and has emitted streams and gases like the carbon dioxide, and the sulfur dioxide, and hydrogen chloride, and hydrogen sulfide.
The streams are formed by the boiling of the superheated water and its pressure falls when it reaches the ground surface.
A geyser is a spring that is characterized by the discharge of the water ejected turbulently and is accompanied by a stream and exists at a few places on earth.
A hot spring is a hydrothermal vent that is made by the emergence of the geothermally heated groundwater that rises form the earth crust.
A travertine is a terrestrial sedimentary rock that is formed by the precipitation of the carbonate materials form the solution to the ground surface and a geothermally heated ground spring.
During the first phase, the population growth rate rises as the death rate declines while the birth rate remains high. In the second phase, the growth rate declines (but remains positive) due to a decline in the birth rate.
