The first answer, 78451-26, is a radiology code for myocardial perfusion imaging. It is possible that just the professional component is being done. This would be coded with modifier -26, so that looks okay.
Next we have, 68520, which is excision of a lacrimal sac, which could quite plausibly done on the right side, so -RT looks okay.
Then, we see 20985, which is an add-on code. According to the guidelines (see Appendix A under modifier 51), modifier -51 should not be used with add-on codes. Answer C violates CPT guidelines.
Of course, 00120, is an anesthesiology code, and the -P1 indicates a normal healthy patient. So this code/modifier combo is also reasonable.
Now you know, "don't code a -51 with an add-on code."
