Solve the Problem $\mathrm { I } ( \mathrm { t } ) = - 0.1 \mathrm { t } ^ { 2 } + 1.3 \mathrm { t }$

Multiple Choice

Solve the problem.
-The polynomial function $\mathrm { I } ( \mathrm { t } ) = - 0.1 \mathrm { t } ^ { 2 } + 1.3 \mathrm { t }$ represents the yearly income (or loss) from a real estate investment, where $t$ is time in years. After what year does income begin to decline?

A) $5.5 \mathrm { yr }$
B) $6.5 \mathrm { yr }$
C) $13 \mathrm { yr }$
D) $8.67 \mathrm { yr }$