What Is the Difference Between the Yield-To-Maturity (YTM)and the Realized

What is the difference between the yield-to-maturity (YTM) and the realized compound yield (RCY) ?

A) They are actually the same concept.
B) The YTM is the actual return,whereas,the RCY is the expected return at the beginning of the investment.
C) The RCY is the actual return,whereas,the YTM is the expected return at the beginning of the investment.
D) The YTM considers only coupon payments,whereas,the RCY includes all the bond's cash flows.