Answer:
sophisticated irrigation, chemical fertilizers, chemical pesticides
Explanation:
The use of irrigation to provide needed water and the use of natural fertilizers to promote crop growth are farming methods that have been practiced for centuries. More sophisticated irrigation techniques, various chemical pesticides, and modern chemical fertilizers have been developed in the twentieth century. 
 
        
             
        
        
        
The propositions are:
a.alkylating agents
b.antimetabolites
c.topisomerase inhibitors
d.nucleoside analogs
e.<span>AZT
The right answer is A, 
An alkylating agent is a compound capable of adding alkyl groups to various electronegative groups under conditions present within the cells.
Antimetabolites are an anticancer drug but act differently than the alkylating agent. (interfere with folic acid)
Topoisomerase inhibitor acts by inhibiting isomerase, used in antibiotherapy (like quinolones).
Nucleoside analogs are analogs as their name says, it does not alkylate nucleotides.
AZT (</span><span>Zidovudine) is an antiretroviral drug that inhibits reverse transcriptase.</span>
        
             
        
        
        
It is B I think 
Hope this helped
        
             
        
        
        
soil, rock, organic layer
Explanation:
Permeability is the ability of a layer of rock to transmit fluid such as oil or water
The factors that affect the permeability of a rock layer includes the sizes of the rock particles, the ratio of the available voids to the solid mass of the rock, the presence of trapped air and the presence of organic matter
Rocks such as gravels, and  sparingly cemented sands have high permeability
The most impermeable of the options are granite and clay which for granite has large particle mass and contain no voids while clay has very fine particles packed together with little room for water
Therefore, water moves easily between layers  soil, rock, organic layer
 
        
                    
             
        
        
        
A. Extinction is a natural part of life on earth