There are four major classes of mortgage$-$related securities$.$ These classes are: mortgage$-$backed bonds $($MBBs$),$ mortgage pass$-$through securities $($MPTs$),$ mortgage pay$-$through bonds $($MPTBs$)$ and collateralized mortgage obligations $($CMOs$).$ Assume you are looking to make an investment in one of these classes. Which class would you choose to invest in$?$ Provide a summary of that class. Explain why you chose to invest in this security over the other options available.