The statement (p→q)→[(∼p→q)→q] is
a tautology
equivalent to ∼p→q
equivalent to p→∼q
a fallacy
The truth table of the given expression is given below:
pqx≡p→q∼p∼p→qy≡(∼p→q)→qx→yTTTFTTTTFFFTFTFTTTTTTFFTTFTT Hence, it is a tautology.