What effect does adding extra water have on pastries?

Adding extra water to pastries generally makes the dough tough and leathery, which can result in shrinkage. This occurs because excessive moisture can lead to overdevelopment of gluten, a protein that provides structure. When too much water is combined with flour, the gluten forms more than desired, creating a rubbery texture rather than a light and flaky one. As the dough is manipulated during mixing or rolling out, it may also become difficult to shape and will shrink back when baked, resulting in a finished product that lacks tenderness and the desired flakiness of a well-made pastry.

The other options address various aspects of pastry making, but they do not align with the reality of adding too much water. For instance, making dough softer and fluffier typically requires just the right amount of moisture, while enhancing flavor is more related to the ingredients used rather than the water content itself. Improving dough's elasticity can indeed be a consideration, but too much water can disrupt the balance leading to an undesirable outcome. Thus, the specific consequences of excess water consistently point to toughness and shriveling in pastry dough.