With the recent growth in the number of U.S. households wired for cable television, major advertisers are now beginning to show an increased interest in cable advertising.Since its inception, cable television has offered advertisers relatively inexpensive rates and selective target audiences.For purposes of comparison, A.J. Bush and J.H. Leigh conducted a content analysis of television commercials on the three major networks, ABC, CBS, and NBC, and three of the more popular, well-established cable networks, CNN, ESPN, and TBS.One of the variables measured was the number of advertisements shown during prime-time (7:00 - 10:00 P.M.) and late-night (10:00 P.M. - 12:00 A.M.) viewing segments on two weekday evenings during November 2003.The results are summarized in the table attached.

Suppose an advertisement is selected at random from advertisements shown on the two weekday evenings during November 2003.What is the probability that the advertisement selectedwas shown on CNN?

a) 95/917

b) 155/518

c) 95/518

d) 155/917