Answer: The correct option is (D) $21.77.
Step-by-step explanation: Given that Heather has $45.71 in her savings account and she bought six packs of markers to donate to her school. Each pack of markers cost $3.99.
We are to find the amount of money that she has in her bank account after the donation.
Cost of 1 pack of marker = $3.99.
So, the cost of six packs of marker = $(3.99 × 6) = $23.94.
Since there was $45.71 in her savings account before the donation, so the amount of amount of left after the donation is given by

Thus, the required amount of money left in her saving's account after the donation is $21.77.
Option (D) is CORRECT.