A one-foot stick is marked in 1/6 and 1/8 portion.

marking of stick in 1/6 portion=
1/6......2/6........3/6.......4/6.........5/6.........1 it can be reduced to
1/6......1/3........1/2.......2/3.........5/6.........1

marking of stick in 1/8 portion=
1/8.......2/8........3/8........4/8.........5/8........6/8.......7/8.......1 it can be reduced to
1/8.......1/4........3/8........1/2.........5/8........3/4.......7/8........1

We can observe that there is an overlap in marking at 1/2. In other cases we have markings at different points
so total points = start point + 5(points for 1/6 marking) + 7 (points for 1/8 marking)- 1 (overlap of two markings at 1/2) + end point
= 1+5+7-1+1
=13
Ans = D