The church's response to feudalism included various measures aimed at addressing its challenges and excesses. Among the options provided, the best choice that was specifically meant to counteract what the church viewed as the "general failure of feudalism" is:
D. the truce of god
The Truce of God was a movement initiated by the church during the medieval period that sought to limit the violence and warfare endemic to feudal society, particularly by regulating when and against whom knights could fight. This initiative was designed to protect non-combatants and to create periods of peace, thereby promoting moral order and reducing chaos, which the church saw as a failure of feudalism.
Commendations, homage, and the fief system, while relevant to the structure of feudalism, did not specifically address the church's concerns about the consequences of feudal conflicts. Thus, the Truce of God stands out as a direct response to the perceived issues linked with feudal practices.