Which of the following can result from inaccurate tensioning in concrete?

The selection of uneven camber and insufficient product strength as the result of inaccurate tensioning in concrete is indeed the most accurate choice. Inadequate tensioning can cause variations in the curvature and profile of the concrete structure, leading to uneven camber. This unevenness can compromise the structural integrity, resulting in insufficient strength to support the loads it is designed for.

When tension is not properly applied, the balance between compressive and tensile forces within the concrete can be disrupted, making certain areas more susceptible to failure. This importance of accurate tensioning is critical in structural applications such as beams, slabs, and pre-stressed elements where precise force application distributes loads evenly.

While the other options present potential issues that can occur in concrete structures, they do not directly relate to the specific consequences of improper tensioning. For instance, reduced thermal resistance and enhanced water resistance pertain to the material properties and mix design rather than the effects of tensioning. Decreased durability and flexibility could result from various factors unrelated to tensioning specifically. However, the most immediate and relevant concern pertaining to inaccurate tensioning clearly aligns with the outcome of uneven camber and insufficient strength.