For a passive investor, the minimum-variance portfolio of country indexes is optimal? Is this true or false.

Question:

For a passive investor, the minimum-variance of country indexes is optimal?
Is this true or false. Explain your answer.
Portfolio
A portfolio is a grouping of financial assets such as stocks, bonds, commodities, currencies and cash equivalents, as well as their fund counterparts, including mutual, exchange-traded and closed funds. A portfolio can also consist of non-publicly...