Final answer:
The total resistance when two light bulbs are connected in series is 1200 Ω.
Step-by-step explanation:
When two resistors are connected in series, their resistances add up to give the total resistance of the circuit. In this case, the resistances of the two light bulbs are 400 Ω and 800 Ω. To find the total resistance, we simply add these two values:
Total resistance = 400 Ω + 800 Ω = 1200 Ω
Therefore, the correct answer is option 1) 1200 Ω.