This is because it is a monocot and monocots do not have a vascular cambium in their stems.
Answer: E. Polygenic
Explanation: The color of eyes and hair is due to quantity and accumulation of pigments such melanin. Melanin is synthesize by multiple enzymatic steps and every enzyme is codified by a different gene. That means polygenic inheritance, that several genes are implicated in determined the this trait and its difficult to trace since every gene has a sequence that can vary between families or human groups.
I'm pretty sure the answer is true. Hope this helps!
