The question requires a substitution for the underlined part of the sentence: "He was extremely unhappy because of the inordinately delay."
The options for substitution are:
To determine the correct substitution, we need to analyze each option:
Conclusion: Option (b) "the inordinate delay" is grammatically correct and fits the context of the original sentence, correctly replacing the underlined portion.
Therefore, the correct answer is: "the inordinate delay"