Caste system is another example of.

a is correct

hope this let me know if it is right

the nationalists wanted a strong central government so the new country wouldn't fall apart.

- r3ktforgood ☕

the answer to fill in the blank in this question would be the word resource, it is defined as the money, material or people (since human resource is a very valuable good) that a company or a person has at disposition (meaning they can use the resource as they see fit), to be able to complete a task or achieve a goal.  

four sitting presidents have been assassinated while in office but the first was abraham lincoln,