CFAI Reading 18 EOC #3 - help understand, all, represents, question, please

YAhmed

Hi all!
I can’t understand the answer for EOC Reading 18 question # 3A. Why was 1.0% spread of 10yr gov’t over 1yr gov’t was added to the Corporate bond, but to the MBS bond. As I understand, this spread represents a maturity risk.
Can some of you please explain?
Many thanks!

hoangvu90

please read the fine print below the question.