Which of the following is a correct formula when markup is based on selling price

You have been given the assignment of speaking about the affects of illegal drug use on youth in america. which of the following types of research is likely not to be necessary while preparing for your speech? a. a government website with statistics on convictions for possession among adolescents under the age of 18 b. a library book about the pharmaceutical drug industry in america c. a recent article from cnn.com about a special home for teenagers addicted to drugs d. a website that provides support for parents whose children are in rehab

Can someone me answer this english question

Dogs make wonderful pets because they us stay happy and healthy. the topic sentence is "dogs make wonderful pets." , is this correct? i keep doubting myself.