since Option defines Arity, Option<T> does not need to

src/System.CommandLine.ApiCompatibility.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt

@@ -205,7 +205,6 @@ System.CommandLine
     .ctor(System.String[] aliases, Func<System.CommandLine.Parsing.ArgumentResult,T> parseArgument, System.Boolean isDefault = False, System.String description = null)
     .ctor(System.String name, Func<T> defaultValueFactory, System.String description = null)
     .ctor(System.String[] aliases, Func<T> defaultValueFactory, System.String description = null)
-    public ArgumentArity Arity { get; set; }
   public static class OptionExtensions
     public static TOption AddCompletions<TOption>(this TOption option, System.String[] values)
     public static TOption AddCompletions<TOption>(this TOption option, System.Func<System.CommandLine.Completions.CompletionContext,System.Collections.Generic.IEnumerable<System.String>> complete)

src/System.CommandLine/Option.cs

@@ -83,7 +83,7 @@ public string? ArgumentHelpName
         /// <summary>
         /// Gets or sets the arity of the option.
         /// </summary>
-        public virtual ArgumentArity Arity
+        public ArgumentArity Arity
         {
             get => Argument.Arity;
             set => Argument.Arity = value;

src/System.CommandLine/Option{T}.cs

@@ -60,12 +60,5 @@ public Option(
             : base(aliases, description, new Argument<T>(defaultValueFactory ?? throw new ArgumentNullException(nameof(defaultValueFactory))))
         {
         }
-
-        /// <inheritdoc/>
-        public override ArgumentArity Arity
-        {
-            get => base.Arity;
-            set => Argument.Arity = value;
-        }
     }
 }