Why wouldn't it be henne in this situation?
Both are OK.
It accepted henne.
I'm wondering if one is preferable?
AFAIK it's recommended to use subject forms in formal writing, but honestly it doesn't matter very much.
In some situations there is a difference. For example:
Jag åt mer än hon.
Jag åt mer än henne.
MarcinM85: Tack för bra jämförelse! ("Thanks for the good comparison!").
In Swedish it is: 1. "yngre än henne" or 2. "yngre än hon ÄR". "yngre än hon" is poorly phrased spoken Swedish, and should be avoided in written form.
Are you younger than she is? Duolingo, you have a chance here to teach the correct English translation. Please use it!! There are already enough people saying this sentence incorrectly.
These grammar mistakes drive me wild