Final answer:
In the provided sentence, the word "segregate" means to set apart and isolate resources based on necessity, which corresponds to option C).
Step-by-step explanation:
In the sentence "To achieve a fair distribution of resources, they decided to segregate the available supplies; separating them into distinct categories based on necessity," the meaning of "segregate" is C) To set apart and isolate resources based on necessity. The term segregate typically refers to the action of separating a group from the rest of a community, either by social structures or by law, known as de jure and de facto segregation, respectively. This concept historically applied to racial segregation, most notably during the apartheid era in South Africa and the Jim Crow laws in the United States, where people were legally separated based on race and provided with unequal facilities.
Segregation in the context of resource distribution implies that the supplies are categorized and kept separate, which contrasts with options that suggest blending or combining resources for distribution. Hence, in the context given, segregate does not mean to unite, mix, or keep resources together, but rather to sort and organize them into groups as a means to achieve a fair distribution based on the principle of Distributive Justice, ensuring equitable allocation of necessities.