To find Ms. Tanaka's total earnings for selling 12 televisions, we can substitute \( t = 12 \) into the equation \( 2,500 + 100t \).
Calculating this:
\[ 2,500 + 100(12) = 2,500 + 1,200 = 3,700 \]
Thus, Ms. Tanaka will earn $3,700 for selling 12 televisions this month.
The correct answer is:
$3,700