To solve this problem, we'll determine how much sugar Velma needs for all five bottles of lemonade.

Each bottle requires $\frac{3}{4}$ cup of sugar. Since she needs to make 5 bottles, we multiply the amount of sugar per bottle by the number of bottles:

$5 \times \frac{3}{4} = \frac{15}{4} = 3\frac{3}{4} \text{ cups of sugar}$

So, Velma needs 3¾ cups of sugar.

The correct answer is D. 3¾.

Do you have any questions or need further details? Here are 5 related questions:

1. How much sugar would Velma need for 7 bottles of lemonade?
2. If Velma only has 2 cups of sugar, how many bottles can she make?
3. What is the total amount of sugar needed if she doubles the recipe?
4. How would the calculation change if each bottle required 1 cup of sugar?
5. Can you express 3¾ as an improper fraction?

Tip: When multiplying fractions by whole numbers, it's helpful to first convert the whole number to a fraction (by placing it over 1) and then multiply the numerators and denominators.