Question

Find a basis for the span S of the vectors
(2, 2, 4, 3), (−2, 1, 2, 1), (3, 1, 2, 2), and (1, −1, −2, 0)

So i did this and got it to be ( 2, 2, 4, 3), (2, 1, 2, 1), (3, 1, 2, 2).

Now it wants me to extend my basis to a basis of r4.....How would i go about this? It says as a hint its always possible to use one of (1,0,0,0) (0,1,0,0) (0,0,1,0) (0,0,0,1)