The arrival of corpus linguistics has revitalized

The correct option is: The Writing Of Observation-Based Grammar.

Explanation:
Corpus linguistics involves the study of language as expressed in samples (corpora) of real-world text or speech (real-world data/observations).
Before corpus linguistics, grammar books were often prescriptive or based on artificial, invented examples. The arrival and expansion of corpus linguistics allowed linguists to analyze vast amounts of actual, observed language data.
Consequently, this revitalized and enabled the writing of grammar books and rules based on actual usage and empirical evidence, which is known as observation-based grammar.