[Select] cost is it is the value of what certain resources could have produced had they been used in the best alternative way. [Select] cost could be in terms of time, and also apply to money. It is left up to you to define what is the best alternative use of these resources. The (Select] is that money that you get in the future is [Select] than getting it today because the future is full of (Select] . Therefore, a hundred dollars that you get in the future is worth [ Select] than getting that one hundred dollars today. So that means we have to [Select] that value of the hundred dollars to its present value. Yield to Maturity versus Yield to Call. These are two different ways of figuring out the return you get from a bond and it has to do with the [Select] of the bond. To figure out how much of a return you will get, you are going to calculate its [Select] .. or how much of a return it is going to generate between now and the end of its predetermined lifetime. The bond with a Select] option written into the contract. This lets the issuer buy the bond back early, usually after a waiting period of a few years. In this case, you might not get to hold on to the bond until the end. You would figure out its [Select] which accounts for a callable bond's shorter potential lifetime. Investment grade bonds versus junk bonds, the key here is it all revolves around (Select] risk. Bond rating agencies just placed a letter grade on these different bonds that are being issued by different railroads. Right, A meant Select] , B, middle quality and C, [Select] quality. The word junk causes negative connotations so instead we usually use the word [Select] yield security