Option 4: (C), (A), (D), (B) -> This arrangement creates: "Little did we realise that the seemingly insignificant choices we made each and every day would culminate in an unimaginable transformation of our lives and the world around us" - a grammatically correct and meaningful sentence with proper flow and structure -> correct
Hence, Option 4 -> The sentence begins with the inverted structure "Little did we realise" (C), followed by the object of realization - "seemingly insignificant choices we made" (A), then the time reference "each and every day would culminate in an unimaginable" (D), and concludes with what they culminated in - "transformation of our lives and the world around us" (B). This creates a coherent narrative about how small daily choices led to significant life changes -> correct