1. A professor at UT Dallas conducted an experiment to examine customer satisfaction with eBay (an online auction website). He used two measures -- ease-of-use of eBay's auction mechanism and usefulnessof online reviews -- to segment eBay's customers. Suppose he identified the following two clusters using k-means, each one with 3 customers: What is the center of cluster A?

a)Ease-of-use = 6, usefulness = 5

b)Ease-of-use = 7, usefulness = 5

c)Ease-of-use = 7, usefulness = 8

d)Ease-of-use = 6, usefulness =7