Give the customer segment from the West region that orders the order ID CA-2011-108189.
Region = 'West'
SELECT DISTINCT T2.Segment FROM west_superstore AS T1 INNER JOIN people AS T2 ON T1.`Customer ID` = T2.`Customer ID` WHERE T1.Region = 'West' AND T1.`Order ID` = 'CA-2011-108189'