Answer :
40% (option B)
Explanation:[tex]\text{Percentage increase = }\frac{new\text{ amount - old amount}}{\text{old amount}}\times100[/tex][tex]\begin{gathered} \text{old amount = \$10} \\ \text{new amount = \$14} \\ \text{percentage increase = }\frac{14-10}{10}\times100 \end{gathered}[/tex][tex]\begin{gathered} \text{percentage increase = }\frac{4}{10}\times100 \\ \text{percentage increase = 40\%} \\ \\ To\text{ the nearest tenth, 40.0\% same as 40\%} \end{gathered}[/tex]The rate of increase is 40% (option B)