Why might pastry chefs use crumbs on the bottom of tart shells before baking?

Using crumbs on the bottom of tart shells before baking is a practical technique to prevent sogginess, particularly when the tart will be filled with juicy fruit fillings. When fruits release their moisture during baking, this can lead to a soggy bottom crust, compromising the texture and overall enjoyment of the tart. By incorporating crumbs, which can absorb some of the excess moisture, a barrier is created that helps maintain the integrity of the tart shell. This technique ensures that the tart remains crisp and appealing, making it a preferred practice among pastry chefs dealing with juicy toppings. The other options, while potentially valid in different contexts, do not directly address the primary function of reducing sogginess, which is crucial for maintaining the quality of the dessert.