Suppose that a B+-tree index on branch-city is available on relation branch, and that no other index is available. What would be the best way to handle the following selections that involve negation?
a. σ ¬ (branch-city<“Brooklyn”)(branch)
b. σ ¬ (branch-city=“Brooklyn”)(branch)
c. σ ¬ (branch-city<“Brooklyn” ∨ assets<5000)(branch)