Step 1: Understand reductive ozonolysis.
Reductive ozonolysis of alkenes results in the cleavage of the double bond, leading to the formation of aldehydes or ketones. If methanal (formaldehyde) is a product, the alkene must be a terminal alkene.
Step 2: Identify the structure.
The correct structure of the alkene is \( \text{CH}_2\text{CH=CH}_2 \), which, on reductive ozonolysis, gives methanal as one of the products.
Final Answer:
\[
\boxed{\text{CH}_2\text{CH=CH}_2}.
\]