Option 1 -> Creates a sentence starting with "threat" without establishing what threat, breaking logical flow.
Option 2 -> Begins with "immediate and collective action" without context, making the sentence disjointed.
Option 3 -> Forms: "Climate change, once considered a distant threat is now a pressing global issue requiring immediate and collective action to mitigate its devastating effects on the planet" - complete and logical.
Option 4 -> Starts with "its devastating effects" without establishing what "its" refers to, lacking proper subject introduction.
Hence, Option 3: (B), (A), (D), (C) -> This sequence properly introduces the subject (climate change), contrasts past perception with current reality (distant threat vs. pressing issue), and logically concludes with the required action and its purpose -> correct