Will appreciate if someone can please guide which version of Spark will be used for test as Exam page states both 1.6 and 2.3 are available on cluster.

CCA175 is a hands-on, practical exam using Cloudera technologies. Each user is given their own CDH5 (currently 5.15.0) cluster pre-loaded with Spark 1.6, Spark 2.3

Thank you  in advance for helping me out.