You need to write more code to class to run DoWork() with 30-second intervals

Given the code like this:
while(!loop)
{
//Thread code here
Dowork();
}

You need to write more code to class to run DoWork() with 30-second intervals using minimum resources

Given the code like this:

while(!loop)
{
//Thread code here
Dowork();
}

You need to write more code to class to run DoWork() with 30-second intervals using minimum resources

A.
Thread.Sleep(30000)

B.
Thread.SpinWait(30000)

C.
Thread.QueueUserWorkItem(30000)

D.
Thread.SpinWait(30)