Answer:
Demand and supply
Explanation:
In a market, the demand for a product and the supply of the products affect the price of them.
If a product has limited supply, the price will rise because it is rarer.
If a product has a lot of supply, the price will decrease because it is common.
If product demand is high, prices will rise because sellers want to earn more money.
If product demand is low, prices will sink because sellers need to make some sort of revenue and if the product doesn't sell, they've lost money. If they sell it at a lower price, at least they make some money back.
Of course, there are more factors but demand and supply are the main two, especially in a free market economy.
 
        
             
        
        
        
Good question.. but you don’t really explain the question
        
             
        
        
        
Well a paragraph is a group of sentences that center around a topic or Central Idea So the answer would be B because if the story is about space and a there is a paragraph about horses that isn't a proper essay and you always need to stick with a central idea to get an A+
        
             
        
        
        
B: personal opinions 
Because readers can have different opinions and it makes an essay more biased.