An Academic Political Researcher Would Be More Apt to Use

An academic political researcher would be more apt to use which of the following poll types in order to obtain reliable information?

A) random-digit dialing in which calls are placed to landlines and cell phones
B) scientific surveys with randomly selected respondents and multiple random survey instruments
C) Internet-based polling of large numbers of respondents with little respondent filtering
D) well-designed exit polls administered in a particular set of purposely selected precincts