This story is centered around the Doctor's response to trolley problems, which makes for a very compelling story, though I'm not sure if I agree with this interpretation.

Deimos: C. The Resurrection of Mars: A.

Gonna be honest, this was a very forgettable story. Tamsin wasn't likable, the Ice Warriors were bland, and there sidecast had few standouts other than David Warner (yippie!) and Tracy Ann Oberman (boo!). This exists solely to build up to the next part and that's fine. 4/10.