Feudalism declined during the crusades because
the catholic church called for its end.
many knights lost their lives and fortunes in battle.
the catholic church took control of european governments.
many knights decided to rise up against their kings.

many knights lost their lives and fortunes in battle.

Explanation:

From the Crusades movement (between the eleventh and thirteenth centuries), a series of eight religious, economic and military expeditions organized by the Church (where there was a great loss of life and wealth), commerce intensified and the commercial revival emerged in Europe.

The commercialization of products with the East from the opening of the Mediterranean Sea was a determining factor for the fall of the feudal system, with the increase of commercial routes.

Although from the religious point of view they did not reach many objectives, the Crusades favored the commercial development, putting an end to Arab domination in the Mediterranean Sea.

many knights lost their lives and fortunes in battle

the us constitution is a living document, meaning that it can be changed over time as the country changes.

i would go with the last one