[单选题]
The last page of a book is numbere,jl bl 18dxzd*d 764.(r m/(el(s(kd meach sheet is double-sided) The book is 3.00 cm mr(d(l/s e(km thick. What is the average thickness of a sheet of paper in the book, in centimeters?
A. $8 \times 10^{-3}$
B. $7.85 \times 10^{-3}$
C. $7.9 \times 10^{-3}$
D. $3.93 \times 10^{-3}$
E. $3.9 \times 10^{-3}$
