The question asks which of the statements is best modeled by exponential growth. Let's analyze the options:

• A. The population grows 5% every year.
  This describes exponential growth because the population increases by a fixed percentage each year. Exponential growth occurs when something grows by a constant percentage over time. The formula would be $P(t) = P_0 (1 + r)^t$, where $P_0$ is the initial population, $r$ is the growth rate (5% or 0.05 in this case), and $t$ is time.

• B. The cost of an apple per kilogram.
  The cost of an apple doesn't necessarily follow exponential growth. Prices can fluctuate or increase, but they are not inherently modeled by exponential growth without more context.

• C. The area of a square of the side $s$.
  The area of a square is modeled by $A = s^2$, which is quadratic growth, not exponential.

• D. The height of a person with respect to his age.
  Human height grows linearly during childhood and adolescence and then stabilizes, so this is not exponential growth.

Answer: A. The population grows 5% every year is the correct choice.

Would you like more details on exponential growth or have any questions?

Here are 5 related questions to deepen your understanding:

1. What are the key differences between linear, quadratic, and exponential growth?
2. How would you model decay processes using exponential functions?
3. Can exponential growth continue indefinitely in real-world scenarios?
4. What is the formula for compound interest, and how does it relate to exponential growth?
5. How would doubling time relate to exponential growth?

Tip: Exponential growth is characterized by a constant percentage increase, while linear growth adds a fixed amount each time.