Answer:
X and Z
Step-by-step explanation:
If the difference in electronegativity between two atoms is greater than 1.7, they will form an ionic bond.
W and Z: 3.2 - 1.5 = 1.7 no
X and Z: 3.2 - 0.93 = 2.27 yes
Y and Z: 3.2 - 2.0 = 1.2 no
W and Y: 2.0 - 1.5 = 0.5 no
X and Y: 2.0 - 0.93 = 1.07 no
W and X: 1.5 - 0.93 = 0.57 no
X and Z are most likely to form an ionic bond together.
Hope this helps.