Answer:
Option B, They lack tubes for transport and support
Explanation:
Non vascular plants do not have the system of tubules (xylem and phloem) that can provide them support or rigidity to become tall. Along with physical support, the transmission of food and water up to greater heights also become difficult due to absence of vascular tissues which further do not allow non-vascular plants to attain great heights.
Thus, option B is correct.