Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

Each composite of a GIPS-compliant firm must consist of:
Option A:multiple portfolios.
Option B:portfolios selected on an ex post basis.
Option C:portfolios managed according to a similar investment strategy.

Answer: C