Answer:
d) Installment sales contract
Explanation:
A contract is described as an agreement between two or more parties commits to undertakes specific obligations.  In a sale contract, the buyer and seller agree to the exchange or foods or services for a consideration called price. 
An installment sale contract is an agreement that allows the buyer to make payment for the goods or services over time. Once an agreement has bee reached, the buyer takes possession of products and is free to use them. The buyer makes regular payments for the goods (installments) and will claim ownership upon completing payments. An installment sale contract is a form of credit sale.
 
        
             
        
        
        
It is u the definition is u its just u
        
             
        
        
        
<span>practice effects and also collaborating </span>
        
             
        
        
        
Answer:
b. the Columbian Exchange.  
Explanation:
The transatlantic flow of people and goods such as corn, potatoes, horses, and sugarcane is called the Columbian Exchange.
The Columbian exchange or interchange, refers to the monumental flow of humans, plants and animals between the continents of North and South America and West Africa; and was named after Christopher Columbus.
The Columbian interchange has been documented to have taken place in the in the 15th and 16th centuries: also referred to as 'the old world'