Why did Octavian adopt the title “Augustus” when the Senate names him Emperor of Rome?

Instead of following Caesar's example and making himself dictator, Octavian in 27 BC founded the principate, a system of monarchy headed by an emperor holding power for life. His powers were hidden behind constitutional forms, and he took the name Augustus meaning 'lofty' or 'serene'.

or

Upon his adoption, Octavius assumed his great-uncle's name Gaius Julius Caesar. ... Historians usually refer to the new Caesar as Octavian during the time between his adoption and his assumption of the name Augustus in 27 BC in order to avoid confusing the dead dictator with his heir.

Explanation:

the triple alliance. germany and austria-hungary were already allies by 1879 when, worried about a threat from russia, they formed the dual alliance. italy joined the group in 1882. there was a concern about a possible attack from france and the alliance needed powerful friends to defend it.