Answer:
b. block.
Step-by-step explanation:
Modified block letter style is a format letter where all text is aligned left, expect the author's address, date and closing.
Block letter style is a format letter where absolutely all text is aligned to the left margin, with no exceptions.
Modified semi-block letter style. In this format, elements from the header and closing are aligned away from the left margin and the body text is justified to the left.
As you can observe from each definition, the one that completes the given statement is block, because in block letter style, all components are aligned to the left margin.