Question: In my coding, i have 4 tasks.
Task A
Task B
Task C
Task D

Task D need to be executed after finish of Task A ,B &C
Task A , Task B ,Task C are Independence and can execute at the same time 

i am now using a sequence approach to perform the action, it take very slow 

```
await Task A;
await Task B;
await Task C;
await Task D;

```

I would like to know if i can make it run concurrently and After finished Task A,B,C ,it will run Task D

Thanks for your help .

Answer: 
```
await Task.WhenAll(new Task[]{Task A, Task B, Task C})
await Task D

```
You can assign the tasks to do the necessary work but not await as they start doing that.

Create a variable and assign it to the task that comes back:

```
var taskA = A();
var taskB = B();
var taskC = C();

```

At this point, they all started in the background and only afterwards we wait them to finish:

```
await taskA;
await taskB;
await taskC;

```

And after the completion of A, B, C, run and wait for it to complete D :

```
await D();

```