Solve the Problem
-The Polynomial Function $\mathrm { I } ( \mathrm { t } ) = - 0.1 \mathrm { t } ^ { 2 } + 1.8 \mathrm { t }$

Multiple Choice

Solve the problem
-The polynomial function $\mathrm { I } ( \mathrm { t } ) = - 0.1 \mathrm { t } ^ { 2 } + 1.8 \mathrm { t }$ 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) $8 \mathrm { yr }$
B) $18 \mathrm { yr }$
C) $12.00 \mathrm { yr }$
D) $9 \mathrm { yr }$