Answer: d) b║d is not true
Explanation:
I love visual aids for questions like these so please see the attachment.
Based on the diagram, we can see that:
a ⊥ e (a)
a║ c (b)
a ║ d (c)
However, b ∦ d, but is instead b ⊥ d.
If we reread the question, we will realize that since b ⊥ c and c ║ d, the it implies that b must be ⊥ to d.