Cherry is to blossom as:Checkout is to purchaseProtein is to shakePaint is to mixPaper is to book

To analyze the analogy "Cherry is to blossom," we need to identify the relationship between "cherry" and "blossom." A cherry tree produces blossoms, which are the flowers that eventually develop into cherries.

Now, let's examine the given options using the same relational reasoning:

1. Checkout is to purchase: A checkout process typically leads to a purchase, similar to how a cherry leads to a blossom.
2. Protein is to shake: Protein can be an ingredient in a shake, but it does not have the same direct relationship as cherry to blossom.
3. Paint is to mix: Paint can be mixed, but the mixing process doesn't directly correlate to producing "paint" in the same manner as cherry to blossom.
4. Paper is to book: Paper is a material used to create a book, but the relationship is not quite the same as cherry to blossom in terms of progression.

Final Analysis:

The analogy that fits best, reflecting the same type of relationship (a source or precursor to something else), is Checkout is to purchase. This is because just as a cherry leads to a blossom (a developmental phase), a checkout is a necessary step toward making a purchase.

Final Answer

Checkout is to purchase.