Which group advised the magistrates in the Roman Republic?

The Senate was a pivotal institution in the Roman Republic, primarily serving as an advisory body to the magistrates. Its members, typically drawn from the aristocratic class, held significant influence over various aspects of governance, including legislation, foreign policy, and financial matters. Although magistrates had the power to make decisions and enforce laws, they would often look to the Senate for guidance, wisdom, and support, valuing its members' experience and political acumen.

This relationship underscored the Roman political system, where the Senate acted as a stabilizing force, helping to balance the interests of different social classes, particularly between the patricians and plebeians. The Senate's role was crucial in shaping legislation and maintaining the continuity of the republican government, thus solidifying its position as the correct answer to the question regarding which group advised the magistrates in the Roman Republic.