Answer:the decline of lichens is an important indicator of an imbalance in the ecosystem. this research can help system ecologists predict how pollution will affect the entire ecosystem 
Explanation:
 
        
                    
             
        
        
        
The correct answer is letter A.
Rainforest deforestation is contributing to a decline in global biodiversity. Irresponsible logging causes the major destruction of many habitats. As a result, many living organisms that are thriving within these forests are displaced or are killed because they no longer have any place where they can thrive and live in peace with their respective species. Deforestation accounts for most of the major catastrophic natural events that we are experiencing at present.
        
                    
             
        
        
        
A main sequence star is bigger than a neutron star,because neutron stars are remnant degenerate matter from a collapsed star,they are completely made out of Neutrons and are extremely dense,and have a diameter of only a several Kilometers.M<span>ost of them have a mass of 1.35-2 Solar masses.</span>
        
             
        
        
        
Crude oil: Through drilling wells
Coal: Through surface and underground mining 
Natural gas: Through hydraulic fracturing
        
             
        
        
        
<span>The balanced equation for ammonia (NH3) is 3H2 + N2 ď 2NH3. This equation starts from H2 + N2 ď NH3. We have 1 N and 3 H on the right side (the product side) of the equation, so we multiply each by 2 to get 2 N and 6 H. We do this so that we don’t have an odd number of H atoms. We then balance the left side (the reactant side) of the equation with the right side, N is already balanced, but we have to multiply H by 3 to get 6 H atoms (to match the right side of the equation.</span>