which is the  best  concluding sentence for this paragraph?

a)still, even with their flaws, web content filters are a vital part of any high school's technology program. b)students need to have access to internet resources today because that is where the future of research and scholarship lies. c)public high schools always have to be on their guard for lawsuits of all kinds--including sexual harassment, abuse, and bullying. d)for example, a student may be doing research on marijuana legalization and thus will search for web sites with the word "marijuana" in them