You are interested in measuring how many children are viewing a new display at the museum. You don't want to interfere with or influence behavior, so you decide to record how many finger prints are left on the glass case at the end of the day. You have been collecting data at the museum. However, each day the fingerprints at the top of the case are cleaned off, leaving only fingerprints from the smallest children near the bottom for you to record. This creates a problem of: Group of answer choices Selective survival Selective deposit Observer bias Experimenter bias Reactivity