Final answer:
The number 454850 in scientific notation rounded to three significant figures is 4.55 × 105.
Step-by-step explanation:
To express the number 454850 in scientific notation rounded to three significant figures, we need to place the decimal point after the first non-zero digit and count three digits from there. This gives us 4.54850, but rounded to three significant figures, it becomes 4.55. Next, we count the number of places the decimal point has moved from its original position, which is 5 places to the left. Therefore, in scientific notation, the number is written as 4.55 × 105. Out of the given options, the correct one is A. 4.55 × 105.