Teacher: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
Teacher: Now, understand the problem? If you are still confused, see the following example:
The Inheritance Cycle is a series of fantasy books written by Christopher Paolini.
Solution: The Inheritance Cycle is a tetralogy of young adult high fantasy novels written by American author Christopher Paolini.
Reason: The output sentence elaborates on the input sentence without changing its general meaning e.g. "tetralogy of young adult high fantasy novels".

Now, solve this instance: Constitutional economics tries to explain the selection of constitutional rules " limiting the choices and activities of economic and political agencies . "
Student:
Constitutional economics is a research program in economics and constitutionalism that has been described as explaining the choice " of alternative sets of legal-institutional-constitutional rules that constrain the choices and activities of economic and political agents " .