I'm on SW 2017.
I've been searching for hours on how to foreshorten this dimension, but no luck.
Some of the methods I've done:
1) enlarge Detail B, then chose the dimension I need, then reduce the detail circle (which is what is in the picture below)
2) I right clicked the dimension line, hoping there would be a foreshorten option, but no.
3) In document properties, made sure all foreshorten options are checked under "automatic"