Please help me with this

Ab+cd-> ad+bc is what kind of reaction

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.

Which criteria should andreas use when evaluating which monitor to purchase? check all that apply1. cost of monitor2. quality of monitor 3. doctor's recommendation4. whether it meets his requirements5. advertiser's claims