We discussed the counting systems of several languages. One could argue that all of the languages we looked at $($including English$)$ group their counting systems based on the fingers$/$hands$.$ One language, Venture$$o$,$ had a base$-$grouping system of $4,$ not $5$ or $($like English$)10.$ Why is it believed that Venture$$o counting is based on the hands if it is base$-4($instead of base$-5$ or base$-10,$ which are globally more common$).$

Because they are counting one number for each hand $+$ foot $($four total$).$

Because the middle finger and ring finger are counted together.

Because they don't treat the thumb as a 'real' finger.

Because they are counting the spaces between the fingers on one hand.