Here is my diagram. Because each person must use 3 flower types to fill 4 spaces, I know that one flower will be used twice. I represent this with the first two spaces next to each person. The next two will be individual flower types.
S: R R _ _
T: G/ _ H G/
U: H H R _
W: G G _ _
Z: _ _ H R
Let's go through the answer choices.
A. I don't see anything that prohibits Tabitha from using lilies. She could use two lilies and one gardenia, or two gardenias and one lily.
B. Can Tabitha use roses? We know that she cannot use two roses because of the first rule: Solomon and no one else uses two roses.
Can she use one rose? Note that she already has one hyacinth. This would give her H and R, which is in violation of the 5th rule: Zepi and no one else uses exactly one hyacinth and exactly one rose. This is why B is the correct answer.
C. Nothing to prevent Solomon from having one lily.
D. Nothing to prevent will from using a hyacinth, as long as he uses a lily and not a rose.
E. Will can use one rose, as long as he uses a lily and not a hyacinth.
