The advantages of vascular tissue over non vascular tissue are evident in

A. Whether organisms have alternation of generations

B. An organism's size and complexity

C. The number of individual offspring produced by each organism

D. All of the above

The answer is for sure "B", based upon logic and common sense.

A bacteria for example are only capable of diffusing nutrients through their walls, which is easy to do for a one celled organism, but would be very difficult with a multi cell organism. And we can safely ignore the other two options because a bacteria is just as capable of reproducing itself without vascular, in fact doing it with very efficiently.