The question seems to refer to a table or list in a parliamentary context, where `X` is a place that requires to be filled. The correct answer is option 3 "Not more than 20 representatives of Union Territories". This option suggests a fact that there could be representation from Union Territories in the Parliament, up to a maximum limit of 20 representatives. This follows the structure of parliamentary representation of various groups in the Indian context.

Option 1 refers to Ministers who are not initially part of the Parliament but need to earn a place within six months of assuming office, which does not fit the standard form of representation.

Option 2 postulates a scenario where there are not more than 20 nominated members, which may not be specific in terms of `who` these members are or `why` they are nominated.

Option 4 is not suitable as it describes the Attorney-General who contributes to House proceedings but isn`t necessarily a representative member in the standard sense.

In conclusion, `X` seems to represent a category of membership, the one that best fits is option 3 as it follows parliamentary membership rules.