System Preferences in OS X is the equivalent to Control Panel in Windows

In a Date placeholder, click the date ________ to open the calendar

A) square B) arrow C) circle D) mark

Consider the following set of two-dimensional records:

Also consider two different clustering schemes: (1) where Cluster 1 contains records {1, 2, 3} and Cluster 2 contains records {4, 5, 6} and (2) where Cluster 1 contains records {1, 6} and Cluster 2 contains records {2, 3, 4, 5}. Which scheme is better and why?