Some political theorists might argue that individual rights must, at times, be sacrificed to promote what?

Some political theorists might argue that individual rights must, at times, be sacrificed to promote the common good.

Explanation:

The common good refers to something that is shared and beneficial for all members of a certain community an individual with its own rights belongs to. To achieve the common good, everyone who belongs to the society should work together to improve the wellbeing of all of its members. If exertion of individual rights in a certain situation may harm the majority, they may need to be sacrificed for the benefit of the majority.

Another words for the common good are commonweal, commonwealth, and general welfare.

your list doesn't mention any of them at all.

and what does "these" mean anyway ?

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).