Option 1: Government formation refers to the process of creating a ruling body in a democracy. While political pressure groups may have influence in this process, it is not their primary function. Therefore, option 1 is incorrect.

Option 2: Political pressure groups do indeed aim to put pressure on the government, but this option suggests that they do so solely for their own interests. However, the correct function of a political pressure group in a democracy is to advocate for the interests and concerns of the people. Thus, option 2 is incorrect.

Option 3: This is the correct answer. Political pressure groups exist to put pressure on the government on behalf of the people and to ensure that their concerns and interests are taken into account in the decision-making process.

Option 4: Making midterm elections is not the primary function of political pressure groups. Their main role is to influence government decision-making, not to directly influence the timing of elections. Therefore, option 4 is incorrect.

In summary, the function of a political pressure group in a democracy is to pressurize the government for the sake of the people.