citizens in Mexico vote for their President is true.
In a presidential system of government, the citizens vote for their President, who is both the head of state and the head of government. The President is elected for a fixed term, usually four years and is not accountable to the legislative body, but citizens have the right to vote him out through the electoral process. This means that the statement "citizens in Mexico vote for their President" is true based on the information provided that Mexico has a presidential system of government.