What algorithm is used to calculate distance between points by default ?

[morzen]

Hello,

I have read the doc https://www.rdocumentation.org/packages/mclust/versions/6.1/topics/hc
and I am still wondering, in a default call for hc() like so:
learned_structure <- hc(imputed_df, score = "pnal")
or even simpler like so:
learned_structure <- hc(imputed_df)

what is used by default to create the cluster and find the distance between points?
is it the Euclidian distance? the Manhattan distance? the maximum distance? or something else ??

kind regards,
BM