Is this correct? Thanks! (AP statistics)

Question 1 (1 point) . Saved The idea that subjects in an experiment change their performance on a task simply because they're being observed is potential bias known as the: replication effect. placebo effect. ) lurking variable effect. Hawthorne effect. cause effect Question 2 (1 point) Saved If subjects in an experiment are separated into groups of Whites and Non-Whites prior to the random assignment stage, we should think of race as a (an): matched pair. ) explanatory variable. bias. blocking variable O response variable. Question 3 (1 point) Saved In a cluster samples O a subset of naturally occurring groups are randomly sampled, ()an alphabetic list of individuals is used for random sclection into the sample. individuals are distinguished based on some characteristic such as gender before O they're randomly selected from the population only convenient members of the population are chosen. None of the above