According to the declaration of independence, when should the people have the right to change their government?
a. when a government wants to raise taxes
b. when the government doesn't protect their natural rights
c. when government officials don't leave office
d. when a king doesn't protect their natural rights

The Declaration of Independence argues that people are "endowed by their Creator with certain unalienable Rights," and that the role of government is to protect those rights. When the government stops doing so, the people have a right to change their government. 

A is wrong because the Declaration doesn't argue that raising taxes is wrong; it argues that the colonists' lack of any say in those taxes is wrong.

C is wrong because the Declaration doesn't mention not leaving office as a specific grievance.

D is wrong because the complaint in the Declaration isn't about the king not protecting rights; it's about the GOVERNMENT not protecting rights.

B is your best answer. The Declaration is very specific about this: "To secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed."