Tall Pine Plywood Company has just received a notice that a shipment of plywood (2 metric tons) has been rejected by Japanese customs because the knotholes commonly found on a plywood sheet are too large. Which of the following categories of nontariff barriers primarily checks such quality issues?
A. Quotas
B. Licenses
C. Embargoes
D. Boycotts
E. Standards
Answer: E. Standards