Tony and Lilly sell magazine subscriptions by telephone. Tony is paid $1.00 for every 5 calls he makes, while Lilly is paid 1 dollar for every subscription she sells, regardless of the number of calls she makes. Tonyl’s telephoning is reinforced on a ________ schedule, whereas Lilly’s is reinforced on a ________ schedule.
variable‑ratio; fixed‑ratio
fixed‑ratio; variable‑ratio
fixed‑ratio; variable‑interval
fixed‑interval; variable‑ratio