Final answer:
To fix the two plural or possessive errors:
Step-by-step explanation:
To fix the two plural or possessive errors:
a. Change 'doctors' to 'doctor's' and 'decades' to 'decade's'. The correct sentence would be: A medical doctor's education requires more than a decade's worth of study.
b. Change 'doctors' to 'doctor's'. The correct sentence would be: After four years of college, a doctor completes four years of medical school.
c. No error in this sentence.