Which ingredient proportion could lead to an unbalanced sandwich?

An unbalanced sandwich can occur when any ingredient is used in excess or insufficient amounts, disrupting the intended flavor and texture harmony. If there is too much meat, the sandwich may become excessively heavy and overpower the other ingredients, making it less enjoyable to eat. Similarly, an abundance of lettuce can lead to a soggy sandwich and diminish the flavor if not balanced with other components. Insufficient spreads also negatively impact the overall experience, as spreads are crucial for moisture and flavor, and without them, the sandwich can taste dry or bland.

Since any one of these situations can result in an unbalanced sandwich, the answer that encompasses all possibilities is the most comprehensive choice. Each listed ingredient plays a vital role in the overall balance of flavor and texture, confirming that unbalanced proportions can arise from any of these factors alone or in combination.