Can cell phone use lead to brain cancer?

which technique would represent the most cost effective approach to conduct an investigation of this research question?
a) do a literature review on previous studies done on this topic.
b) ask friends and family that use cell phone if they have brain cancer.
c) call the cell phone companies and talk to a customer service representative.
d) hire a research firm to write, distribute, collect, and analyze results of a national survey.

answer; i believe the answer is 80%, plz check first good luck;

the answer is the petition of right.

explanation:

offer to of right, real demand of attesting a benefit against the english crown, the most remarkable point of reference being the petition of right of 1628, which parliament sent to charles i fussing of a movement of oversteps of law. the term also implied the framework (invalidated in 1947) by which a subject could sue the crown.   taking a gander at the frameworks used by maria amidu to make a standard in 2015 commending the 1628 petition of right, which was sent to charles i by the english parliament. at uniquely based law the crown, or the sovereign in his official cutoff, couldn't be sued in the ruler's courts. since the ruler was, really, the superior ace of those courts, coordinating value in them between his subjects, he was not subject to their ward. therefore it transformed into a preparation, at whatever point a subject's certified or individual property had come into the responsibility for ruler or his specialists without legitimate perfect, for the subject to engage the master in chamber for its recovery.