What are the different ways to handle concurrency in WCF? | WCF Interview Question

There are three different ways to handle concurrency in WCF that are:
a)    Single
b)    Multiple
c)    Reentrant
Single: means at a given time, only a single request can be processed by WCF service instance. Other requests will be waiting until the first one is fully served.
Multiple: means multiple requests can be served by multiple threads of a single WCF service instance.
Reentrant: means a single WCF service instance can process one request at a given time but the thread can exit the service to call another service.
We can apply these concurrency settings by putting ConcurrencyMode property in ServiceBehavior as follows:

[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple]
public class MyService : IMyService
{
}