Up until a few years ago, the options for R were 15 yards & rekick, awarded FC at the spot, or result of the play. Ralph & his compatriots wisely added the 15+AFC option.
You might argue that "result of the play" isn't really a penalty, but it's still an option.
"The result of the play" is declining the penalty and as Bama said isn't really a penalty option. We didn't take it out, as this long thread illustrates, there may be some situation where it might be beneficial to take the AFC without the yardage (as of yet, no one has figured out when).
Time for a quiz.....when would the clock start
(1) 4th & 6 @50, R fair catches @ R's 30 but is
as 12th R player fails to get off the field prior to snap (doesn't participate).
(2) Same as above, only kick rolls dead at R's 30.
(3) Same field position but K is
for KCI @ R's 10 and R chooses previous spot enforcement.
You make the call....