What is one reason why the House of Representatives has a fixed number of members?

The reason the House of Representatives has a fixed number of members is to allow equitable representation among the states. The total number of representatives is set at 435, and this number is allocated to the states based on their population as determined by the decennial census. This system is designed to ensure that larger states, with more citizens, have more representatives, while smaller states have fewer. This proportional representation helps to reflect the interests and needs of a diverse population across the country.

In contrast to the other options, the idea of equitable representation speaks directly to the principles of democracy, aiming to give each citizen a fair voice in the legislative process. The other reasons suggested, such as ensuring equal treatment for all states or enforcing job security, do not capture the fundamental goal of representation as effectively as the concept of equity does. Balancing power is more relevant to the overall structure of government, primarily between the legislative, executive, and judicial branches, rather than the specific composition of the House.