Inferior Company, which is based on South Carolina, makes and sells products that are poorly made. Jack, who is a resident of North Carolina, buys an Inferior product and suffers an injury through its use. The diversity of citizenship between these parties means that
a. state courts have exclusive jurisdiction.
b. federal courts have exclusive jurisdiction.
c. federal and state courts have concurrent jurisdiction.
d. no court has jurisdiction.

Concurrent jurisdiction between federal court and state court displays having a matter on particular case even though systems are different from each other i.e.- Federal and state court system. More than one court is involved in hearing of case.

According to the question, case of injury caused to Jack (who is from North Carolina) through product of Inferior company (which is South Carolina based company) determines concurrent jurisdiction of state government and federal government.

Other options are incorrect because state and federal courts do not persist exclusive jurisdiction or non-jurisdiction as per question's case.Thus, the correct option is option(c).