Final answer:
True, the return address in a block style business letter begins at the left margin, conforming to the standard block formatting guidelines.
Step-by-step explanation:
The return address in a block style business letter does indeed begin at the left margin. This is in alignment with block formatting guidelines, where everything, including the sender's address, the date, the inside address or recipient's address, the salutation, the body, and the closing, should be left-justified. It's recommended to use a standard business font such as Times New Roman or Arial, at size 11-12, and to ensure the body of the letter is single spaced with a double space between paragraphs.