In the early Roman Republic, the following limited the power of consuls:
- They could serve only one term.
- They were expected to approve one another’s decisions.
These checks were put in place to prevent any single consul from gaining too much power or acting unilaterally.
The other options, "They had to be confirmed by the tribunes" and "They could serve only two years," are not accurate in the context of how consul powers were limited during that time. Consuls were not required to be confirmed by tribunes, and they traditionally served for one year, not two.