The rate of return on the market index went from $14\%$ last year to $19\mathrm{.}5\%$ this year. However, a stock of a manufacturing company witnesses a positive change of almost $21\mathrm{.}5\%$ during this period. Based on the above information, calculate the beta of the company's stock.

$3\mathrm{.}22$

$3\mathrm{.}91$

$2\mathrm{.}91$

$4\mathrm{.}13$