What is a delayed multiple-baseline design? Select one: a. When an initial probe is taken to determine the subject's level of performance on each baseline b. When an initial baseline and intervention are begun, and subsequent baselines are added in a delayed fashion c. When a probe is obtained on each baseline prior to introducing intervention on the next baseline d. When, after criterion-level performance is reached on any baseline, a probe of each remaining baseline is obtained to determine whether performance changes have occurred in any other baselines