Problem Solving

99,999^2 - 1^2 =

A. 10^10 - 2
B. (10^5 - 2)^2
C. 10^4(10^5 - 2)
D. 10^5(10^4 - 2)
E. 10^5(10^5 - 2)

Hi can someone help me out with this problem??

This is what I did:

99,999^2 - 1^2

=> (99,999 + 1)(99,999 - 1) step 1
=> 100,000 (99,999 - 1) step 2
=> 10^5 (99,999 - 1) step 3

now after this im unsure what to do to get one of the answers above.

in another post, (https://www.beatthegmat.com/99-999-2-1-2-t55211.html) i saw that the 99,999 was rounded off to
100,000 & the 1 was increased to 2. hence, the sol is:

=> 100,000 (100,000 - 2) step 4
= 10^5(10^5 -2)

can someone pls explain the logic behind step 3 to step 4? can one increase the value of 2 numbers like this?? thanks!
this question doesn't even ask for an approximation otherwise i would've bought the answer but im not convinced. thanks in advance!