You are adding a public method named UpdateGrade to a public class named ReportCard.
The code region that updates the grade field must meet the following requirements:
It must be accessed by only one thread at a time.
It must not be vulnerable to a deadlock situation.
You need to implement the UpdateGrade() method.
What should you do?

A.
Option A

B.
Option B

C.
Option C

D.
Option D