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1 . Consider a group consisting of 7 girls and 6 boys. Elisa is one of the girls. How many ways are there to arrange these 13 people on a horizontal line such that Elisa has 2 neighbors, both of whom are girls? (The order on the line matters.)
(a)
126510!
(b)
116510!
(c)
136510!
(d)
11(62)10!