2020 Pascal Problem 14

A sequence of figures is formed using tiles. Each tile is an equilateral triangle with side length 7 cm. The first figure consists of 1 tile. Each figure after the first is formed by adding 1 tile to the previous figure. The first four figures are as shown:

How many tiles are used to form the figure in the sequence with perimeter 91 cm?

\textbf{(A)}\ 6\quad \textbf{(B)}\ 11\quad \textbf{(C)}\ 13\quad \textbf{(D)}\ 15\quad \textbf{(E)}\ 23

If there are no answer choices shown, enter a numerical answer.

Full credit to this problem is given to the CEMC, you may view all Pascal contests here.