The time given is \( 8.64 \times 10^4 \) seconds. To express this in standard form, you can calculate it as follows:
\( 8.64 \times 10^4 = 8.64 \times 100,000 = 86,400 \) seconds.
In standard form, this is written as:
86,400 seconds
So the correct response is:
86,400 seconds