The answer for this is Density
        
                    
             
        
        
        
Easy. HISTORY or GEOGRAPHY books of specific areas you want to know more about.
 
        
             
        
        
        
All of these are necessary, but what you need the most I would say is 
D. Movement
Without movement, your body can stiff up, causing muscle problems which can lead to many various things.
        
                    
             
        
        
        
LINKAGE
Independent assortment refers to the allele segregation of two different genes. They are expected to be segregated from each other independently.This is not seen in monohybrids, they are usually heterozygous for an allelic pair only. Link genes cannot assort independently. These are inherited together during meiosis phase of sexual reproduction. Usually genes that are close together will tend to stick together resulting into inheritance of genes as pairs.
        
             
        
        
        
Answer:
<em>1. They effect crop productivity</em>
As weeds start to grow in the area where the crops were destined to grow, the production of the crops gets lowered.
<em>2. They deplete the crops from nutrition</em>
The weeds will compete with the crop plants for resources such as minerals from the soil.
<em>3. They will deplete water resources</em>
The weeds will compete with the crop plants for water.
<em>4. Sun-light will be depleted</em>
The weeds will complete with the crop plants for sun light.
<em>5. The crop quality will be affected</em>
As the crop plants will be in competition with the weeds, hence their quality will be affected.
6.  <em>They can reduce the biodiversity of crop plants.</em>