Answer:
Paragraph B effectively completes the closing section of the message.
Step-by-step explanation:
The second paragraph is detailed, precise and comprehensive in one single breath. It goes thus;
''Therefore, we would like to invite you to be the keynote speaker for the second annual ELY conference. The keynote address is scheduled for 10 a.m., Friday, April 16, in the Jackson High Memorial Auditorium. Our students would be honored by your presence. If you are able to join us, please call me at (555) 673-3333 by March 15 to make arrangements.''
From the forgoing, we not only know the keynote speaker, we are given the exact timing and address for the event. The preciseness, clarity and message of purpose makes it succinctly distinct from option A.
Hence, as a closing remark, the option B has followed the logical sequence expected of a message/mail of such purpose. This is unlike the first option which is not detailed, precise and categorical enough.