While state courts will address violations of state laws, they are not equipped to handle cases in which these cases are in the domain of the federal court system.
a.
there is a conflict between two or more states
b.
decisions are appealed
c.
state judges cannot reach a decision
d.
citizens sue the state government

The correct answer is letter B.  

When cases are appealed it is no longer a case that the state court should handle but of the appellate courts or court of appeals. It is a different part of the federal system that has different varieties of jurisdiction in different states. It is one of the three levels of the court system that primarily reviews the decisions made in a state court or lower court. The final decision about the case is then handled by the Supreme Court, the highest level of the federal system.