'a' is correct, As 'valuable ' is a polysyllable word,' the most' has to be used to form the Superlative degree
Answer: For example, "1+1=2" is a nonsensical proposition. Wittgenstein wrote in Tractatus Logico Philosophicus that some of the propositions contained in his own book should be regarded as nonsense. ... In the name of nonsense, it is finally refused the conception of duality and the Aristotelian formal logic.
In the truth behind bars an Olympic medallist explains from their experience how the visiting athletes are treated by the host country during the Olympic games. By using an in text citation the author has omitted the last name of the author and this is the mistake made.