During the reign of Augustus, the Senate:

Was basically powerless.

Ceased to exist.

Expanded its power.

Led a revolt against the Emperor.

Expanded its power.

Explanation:

In the reign of Augustus, the Senate were allowed to expand its power through series of policy of the emperor. Part of the reason why he did it was inorder to run an on inclusive goverment favourable to the people.

An example, is the ability of the Senate to summon Augustus during their senate meetings to explain some certain policies of his unlike previous reign where such is not possible.