M201 : Quiz of Understainding explain for Sharded Cluster

Hello Community, Good Day !

The Quiz request to choose what are the options and informations that explain output of sharded cluster may show us.
Among the list of the aswers, which is not true, we have :

  • The estimation of the cardinalities of the distribution of the values.
    What does is mean ? Can anyone explain ? I couldn’t fond it by google it, or maybe I don’t know how to search it. Thanks in advance.