Here's a problem to solve: Over time, the ability to ship foods around the world has improved. Which is the most likely effect these shipping improvements have had on people?

Among the 4 following options, which is the correct answer?

- A: They have increased the time it takes to shop for food.
 
- B: They have decreased the number of grocery stores.
 
- C: They have decreased the need for refrigerators.
 
- D: They have increased the types of food available for sale.
 