Definitely Gro B.
I didn't mean that Gro's art was lesser than Benny's - only that as far as pricing goes there is a big difference, at least in Norway.
A piece signed by Benny (not signed "BM Plus" but script initials with YY digits) will typically go for Ā£100 to Ā£1000 whereas a piece signed by Gro may fetch Ā£20-Ā£50,
the apples are fairly common and sell for around Ā£25.
BM's art has been in fashion here for over half a century and interest shows little sign of abating.
Her "Groups in Glass" was a hugely popular series for Randsfjord, and probably remains her most easily recognized design.
I've attached three pieces from the Groups series. These are pretty easy to find, never signed and prices vary from Ā£25-65 depending on size and design.
GB's apples are still popular and sell easily, but I suspect her colorway may be outside of current fashion here.