Answer: A
I20 is the appropriate code for this patient as she is diagnosed with angina and this code codes for angina pectoris.
Option B is not correct because I21 codes for acute myocardial infarction because this is not the diagnosis here.
Option C is not correct because I22 codes for subsequent STEMI and NSTEMI myocardial infarction which is not the diagnosis here.
Option D is not correct because I23 codes for complications due to STEMI and NSTEMI myocardial infarction which is not the diagnosis here.