

If your companion is Tali, she will remove her mask and commit suicide by letting herself fall off the cliff. Your Quarian companion will witness this on the ground, seeing Quarian ships burn up in Rannoch's atmosphere. Their fighters will overwhelm the Quarian fleet and wipe them all out. They will sacrifice themselves to make this happen, and the Geth fleets gain full sentience.

Picking this option will allow Legion / the Geth VI to upload the Reaper Code. Below is how each plays out, and what you need to do in order to unlock the Persuasion options. Once Legion / The Geth VI starts uploading the Reaper code and Tali / Shala'Raan's pleas to call off the attack do nothing, you'll now have up to four options to pick, each with drastically different results.

Similar to Virmire, this is actually a false choice it doesn't matter what you pick here, the true decision comes immediately afterwards.

Initially, you're given the option to pick "Upload the code" or "We're letting the geth die". Tali (or Shala'Raan if Tali died in Mass Effect 2) will protest this decision: since the Quarians are already attacking the Geth, uploading the code will cause the Geth to retaliate and wipe them all out. Legion (or the Geth VI if Legion died in Mass Effect 2) wants to upload the Reaper code to the Geth collective, as it gives them true intelligence. With the Reaper defeated, the Geth are free from its control, and now the Quarian fleet turn their guns at the Geth ships. This scenario takes place in the final mission dealing with the Quarians and the Geth, titled " Priority: Rannoch".
