(Note for eager "close as duplicate": the Archive/ link for this package is (currently?) broken which is very unusual for CRAN so I spelled out alternative approaches below. That part is likely not a duplicate. Cheers. -D.)
CRAN packages are open source, and even when removed from the current CRAN index for reasons deemed necessary by the CRAN team will always remain available in the Archive/ section of the package.
So the link you provide has as its second line
Formerly available versions can be obtained from the archive.
where the archive link should provide you access to various versions.
However, it is not working, which looks like an error. So I just alerted CRAN to that.
I happen to have maintained fOptions in Debian for a number of years. So you still get the Debian binary packages -- and sources. Most recent versions are at https://packages.debian.org/sid/r-cran-foptions point for example to the source archive: http://deb.debian.org/debian/pool/main/f/foptions/foptions_3042.86.orig.tar.gz
If you can install from source this should do.
Otherwise, there is also a CRAN mirror at GitHub so
https://github.com/cran/fOptions is another choice.