The correct answer is B. Modified block
Explanation:
Business letters are a formal tool of communication between companies or between organizations and customers, as these are formal papers they usually follow strict formats and are written for different purposes that include request information, order supplies, reply, among other. Regarding formats, the most common are block format in which all the content of the letter is aligned to the left and modified block in which most of the content is aligned to the left except the date, author's information and closing which are in the center. Another no so commonly used formats include open format, semi-block and modified semi-block in which text allegation and indentation varies in different ways. As a consequence besides block, the modified block is the most common formats used for business.
