Question : Find errors of pronoun.
It is a well-known fact that one must not reveal their secrets to people who do not care.
Option 1: that one must not reveal
Option 2: their secrets to people
Option 3: who do not care
Option 4: No error
Option 5: It is a well-known fact
Correct Answer: their secrets to people
Solution : One is a singular subject. Thus, the usage of ‘their’ is wrong here.