Where in the Following DNA Sequence Is the Start of a 6-Base

Where in the following DNA sequence is the start of a 6-base type II restriction site? Every fifth nucleotide is indicated with a bold letter using the top strand for numbering. 5' A C T T C A G A A T T C C T T A C G A A G T T A T C 3'
3' T G A A G T C T T A A G G A A T G C T T C A A T A G 5'

A) 1
B) 7
C) 10
D) 18
E) there is no restriction site in this sequence