The nascent industry, initially dismissed by many as a fleeting trend, has since experienced _____ growth, fundamentally altering the economic landscape and creating numerous unforeseen opportunities.

✓ Correct Answer: Option B

The phrase 'fundamentally altering the economic landscape and creating numerous unforeseen opportunities' suggests remarkable, never-before-seen growth. 'Unprecedented' best captures this idea of growth that exceeds all previous benchmarks. 'Protracted' means lengthy, 'tentative' means uncertain, and 'ephemeral' means short-lived, none of which fit the significant impact described.