10 Smartest Decisions In Sci-Fi Movie History

3. Handing A Grenade To The Doppelganger - Annihilation

Annihilation is one hell of a sci-fi head-trip, and concludes with soldier Lena (Natalie Portman) reaching the Shimmer, the source of the extraterrestrial anomaly that has been causing grotesque mutations to the surrounding area.

Inside the nearby lighthouse, she witnesses Dr. Ventress (Jennifer Jason Leigh) transform into a nebulous object which, after taking a drop of Lena's blood, mutates into a metallic doppelganger of her.

As Lena attempts to escape the lighthouse, the doppleganger mimics her movements in an attempt to stop her escaping, even nearly suffocating her against the wall.

But Lena has one very clever idea: with seemingly no way to fend off the doppelganger, she decides to grab a phosphorus grenade and hand it to the clone, which by copying her movements it gratefully accepts.

Lena then flees at the very last minute, while the doppelganger is left to burn with what remains of the Shimmer. Talk about cleverly improvising a solution to a situation that could've easily resulted in her death.