Final answer:
The Spanish adopted Escandón's colonization tactics because the mission and presidio system failed to extend Spanish control over Texas, making his alternative strategy for settlement and security more appealing.
Therefore, option D is correct.
Step-by-step explanation:
The Spanish were willing to use Escandón's colonization tactics in Texas because the mission and presidio system largely failed to establish Spanish control of Texas. Considering that the Spanish objective was to colonize and secure their territories, when their initial systems of missions and presidios (military outposts) did not adequately extend their influence or control over the region, they turned to alternative strategies like Escandón's tactics. These tactics were geared towards more practical and flexible settlement policies, including recruiting empresarios like Moses Austin, who would bring settlers in exchange for land grants. This method allowed Spain to increase the non-Native population, create a buffer zone against Native American tribes, and provide a bulwark against American expansion. Given that Escandón's methods seemed more viable for achieving these goals against the backdrop of a changing North American political landscape, Spanish officials adopted them as part of their colonial strategy.