Establish/Maintain a Formal Explanatory Style Practice Test

The writer is drafting a formal social studies report about the three branches of government. Which sentence should be revised because it is too informal?

The passage is part of a class report about the Roman Republic: “The Roman Republic established elected leaders and a Senate to govern the state. Laws were recorded to support consistent decision-making. You can totally tell they were serious about rules.” Does the passage maintain a consistent formal style?