Answer:   By using the SynchronizedCollection has a built-in synchronization object which can be used to make collection thread-safe, and this can be used for specific requirement.

Answer:   Collections classes can be made thread safe using any of the following methods:

Create a thread-safe wrapper using the Synchronized method, and access the collection exclusively through that wrapper.

If the class does not have a Synchronized method, derive from the class and implement a Synchronized method using the SyncRoot property.