The answer is C: clade 4 was derived from clade 2. The easiest way to interpret this cladogram is to start from the base and work up the first branch which is the earliest known common ancestor (1). From 1, two more distinct ancestors evolve (2 & 3), indicated by the next level of branching. 2 gives rise to 4, and 5, which give rise to A and B, and C and D, respectively. Similarly, 3 can be interpreted in the same way.