The correct order of the paragraphs is B, C, A.
Here's why:
* **B:** This paragraph introduces Lenny's best friend, Zach, and establishes that they are both similar and different.
* **C:** This paragraph elaborates on the differences between Lenny and Zach (age, food preferences, academic strengths).
* **A:** This paragraph describes the activities they enjoy doing together and mentions another difference (Zach is faster).
Thus, the correct order is B, C, A.