Final answer:
According to E. E. Schattschneider, the interest-group system has a strong upper-class bias.
Step-by-step explanation:
E. E. Schattschneider argues that the interest-group system has a strong upper-class bias. This means that the system tends to favor the interests and concerns of the upper-middle and upper classes over those of other social groups. These groups have more resources and time to invest in political activities, which gives them an advantage in shaping policies and decisions.