Under which condition is an unexpected competitor most likely to introduce a new business model that disrupts the market of a strong and established firm?

$$ When environmental forces affecting the firm's customers change the primary benefits that are important to them

When a large segment of the firm's current customers would prefer a different set of benefits but they're not available elsewhere

When the established firm loses focus and no longer delivers a discernable value to its existing customers

When economic factors raise costs to the point where the value equation is no longer positive