Which survey question is unbiased? will give brainliest for person who shows

a) do you think we should allow them to cut down them to cut down the trees and pave over the grass for the new playground?
b) which do you prefer with a meal water, or a syrupy sweet soft drink?
c) should there be a school dress code?
d) do you prefer bringing a healthy lunch to school or eating cafeteria food?