Slip Stitches Again

Gift Bag in a version of Garter Slip Stitch

Using multiples of 2 + 1 stitches cast on

1st row (right side): Knit
2nd row : Knit
3rd row: K1, *sl 1 purlwise, k1; rep. from * to end.
4th row: K1, *yf, sl 1 purlwise, yb, k1; rep. from * to end.
Rep. these 4 rows.

The trick is in the order of the colour changes.  Options are :
- work rows 1 and 2 in colour A and then 3 and 4 in colour B.
- 2 rows in A, 2 rows in B and 2 rows in C throughout 
- 1 row each in colour A, B, and C throughout