When a comet is close to the sun, the force from the sun's radiation pushing against the comet making a dust and/or gas tail. The comet being close to the sun also forms the coma of a comet due to it's radiation. The only thing that doesn't exist while being close to the sun is the nucleus. In conclusion, When a long period comet is farthest from the sun in its orbit, C. the Nucleus exist.
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Answer:
B) Sea level rises as Earth becomes warmer and glaciers melt.
 
        
             
        
        
        
Secondary succession generally takes place faster in comparison to primary succession as the substrate is already present. In the case of primary succession, there is no soil and it consumes much time to form.  
Primary succession takes place in mainly lifeless regions, that is, the regions in which the soil does not possess the tendency of sustaining life as an outcome of various factors.  
On the other hand, secondary succession takes place in the regions where a community that previously prevailed have been eradicated and is epitomized by smaller scale turbulence, which do not eradicate all the forms of life and nutrients from the environment.  
 
        
             
        
        
        
Answer:
Which of the following mechanisms is used by gram-negative bacteria to cross the blood-brain barrier? D) Inducing TNF
Explanation:
 The blood brain barrier is a barrier formed by brain microvascular endothelial cells, astrocytes and pericytes. Pathogens can cross this barrier by using different mechanisms. The Tumor Necrosis Factor (TNF) is the way gram-negative bacteria cross this mentioned blood-brain barrier.