A construction firm claims that their new brand of concrete sealant, "Durafix," is superior to the current leading sealant because it remains waterproof for fifty years, which is twice as long as the current leading sealant. However, engineering standards state that the maximum lifespan of the structures for which this sealant is designed is only twenty-five years. Which of the following statements, if true, would most seriously call into question the claim made by the construction firm?

As per the construction firm, Durafix is superior because it remains waterproof twice as long as the currently used sealant. But according to the engineering standards, the maximum lifespan for which any structure needs to be sealed is twenty-five years. Thus, any sealant which can keep a structure waterproof for twenty-five years is perfect for this purpose. This means Durafix will not be a better option than the already existing brands of sealant in the market if they can keep a structure waterproof for as long as twenty-five years. Option (a) says that the current leading sealant’s waterproofing ability is more than sufficient to last for twenty-five years. Thus, option (a) is the right answer.