In a classroom experiment, a student rubs a comb against her hair. the comb is then brought near bits of paper resting on a surface. which of these can be concluded if the comb picks up the bits of paper?

a) the comb is an insulator, but paper conducts electricity.

b) the comb had a net charge on it, and it attracted a neutral object.

c) the comb was left uncharged, and it attracted a positively charged object.

d) the comb was positively charged, in attracted a negatively charged object