bpo-9694: Fix misleading phrase "optional arguments" (GH-23858)

diff --git a/Lib/argparse.py b/Lib/argparse.py
index 2fb1da5..8a12dea 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1719,7 +1719,7 @@ def __init__(self,
 
         add_group = self.add_argument_group
         self._positionals = add_group(_('positional arguments'))
-        self._optionals = add_group(_('optional arguments'))
+        self._optionals = add_group(_('options'))
         self._subparsers = None
 
         # register types