Which method must be defined by a class implementing the java.lang.Runnable interface?
public void run()
public void start()
void run(int priority)
Answer: Option B
Option B is correct because in an interface all methods are abstract by default therefore they must be overridden by the implementing class. The Runnable interface only contains 1 method, the void run() method therefore it must be implemented.
Option A and D are incorrect because they are narrowing the access privileges i.e. package(default) access is narrower than public access.
Option C is not method in the Runnable interface therefore it is incorrect.