Step 1: Understanding the word "metamorphosis."
Metamorphosis refers to a process of change or transformation, particularly a dramatic or marked one. It is often used to describe a complete change in form, structure, or appearance.
Step 2: Analyzing the options.
- Option 1 talks about showing off a car, which does not involve any transformation.
- Option 2 involves discarding clothes, which is not a transformation.
- Option 3 describes the transformation of a garden from weeds to a green lawn, which is a perfect example of metamorphosis.
- Option 4 involves painting a house, but there is no mention of a dramatic change in form.
Step 3: Conclusion.
Option 3 best describes metamorphosis, as it involves a dramatic transformation from one form to another.
Thus, the correct answer is 3. A garden full of weeds is converted into a lovely green lawn.
Final Answer:
\[
\boxed{\text{The correct answer is 3. A garden full of weeds is converted into a lovely green lawn.}}
\]