Which ingredient is primarily responsible for the texture of the streusel topping?

The texture of a streusel topping is largely influenced by the combination of sugar, flour, and fat, making the blend of all three the correct choice. Each ingredient plays a distinct role in creating the desired crumbly and crunchy texture.

Flour provides the structural backbone by forming gluten when mixed, which helps bind the mixture while maintaining a crumbliness. Sugar not only adds sweetness but also contributes to the texture by promoting moisture retention and helping to create a crisp topping as it caramelizes during baking. Fat, typically in the form of butter, is crucial as it coats the flour particles, inhibiting gluten formation and providing a tender mouthfeel.

When combined, these ingredients yield the characteristic streusel texture: a balance of crunch and crumble that enhances pastries and desserts. Without one of these components, the texture would be different; insufficient fat might lead to a dry topping, while too much sugar could result in a overly sweet or clumpy mix. Thus, the harmonious blend of all three ingredients is essential to achieving a well-textured streusel topping.