Hi!
The schedule which is most effective for maintaining behavior over the long term is C) Variable Ratio
This schedule consists in the reinforcement of a given behavior after a variable number of desired responses. This produces the highest behavior maintaining. This type of schedule is used in Slot Machines, Video game tokens, and bonuses to salespersons. Behavior reinforced through this schedule is the hardest to extinguish, explaining the difficulty of recovering from ludopathy (adiction to gambling).