With regard to Broadbent's model of attention, which of the following does not belong?

Which of the following is a secondary reinforcer?

a. money b. a bar of candy c. attention d. a drink of water

Many so-called UFOs may actually be caused by ________

a. the Muller-Lyer illusion b. the Ponzo illusion c. faulty monocular cues d. the autokinetic effect