What’s the drawback of optimizing only for online conversions?

You may miss out on potential customers who watched your ad
You may miss out on potential customers who engage across all ad formats
You may miss out on potential customers who show interest in your product.
You may miss out on potential customers who purchase offline only or research online but buy in-store.

The correct answer is:

You may miss out on potential customers who purchase offline only or research online but buy in-store.