Final answer:
The standard practice in formatting letters is to have one return between paragraphs in the body of a letter, but some formats or traditional styles may use two returns for clarity (option A).
Step-by-step explanation:
When formatting a letter, the standard practice is to have one return, or one press of the enter key, between paragraphs within the body of the letter. This creates a visible space that indicates the end of one paragraph and the beginning of another, making the letter easier to read and more professionally formatted.
In more traditional business letters or in certain styles, such as the block format, a line space, or double space, which is effectively two returns may be used to separate paragraphs to provide a clear visual cue and enhance readability.
Hence, the answer is option A.