In a study, students received rats they believed to be genetically bred as "maze-bright" or "maze-dull" rats. for the next several days, students trained and recorded how long it took for their rats to complete a maze. although the rats were genetically the same breed, the "maze-bright" rats showed improvement in their performance every day, whereas the "maze-dull" rats did not. this study is examining which of the following?
a. reactivity
b. observer bias
c. observer effects
d. socially desirable responding

Explain why methicillin resistant staphlococcus aureus (mrsa) is more prevalent now than it was only 30 years ago. a. antibiotics cause mutations in staphlococcus aureus that lead to an increase in the number of methicillin-resistant strains. b. methicillin resistance causes an infection to spread more rapidly. c. frequent and inappropriate use of methicillin-type antibiotics has provided selective pressure that has resulted in an increase in the proportion of methicillin-resistant strains of staphlococcus aureus. d. diseases like aids have made people more vulnerable to infections from staphlococcus aureus.