If Alexa goes to the market every alternate day, that means she visits the market every other day.
In a week, there are 7 days. If she visits every alternate day, she will go to the market on 4 days (Monday, Wednesday, Friday, Sunday).
The given statement mentions that she went to the market yesterday, so it fits with the inference that she goes to the market 4 times a week.
The correct answer is (c) TRUE.