あなたはどっち.erl

%% A
F = fun() ->
      mnesia:table_info(store, size)
    end,
Result = mnesia:activity(async_dirty, F, [], mnesia_frag).

%% B
Result = mnesia:activity(async_dirty,
                         fun() ->
                            mnesia:table_info(store, size)
                         end,
                         [],
                         mnesia_frag).

%% C
Result = mnesia:activity(async_dirty, fun mnesia:table_info/2, [store, size], mnesia_frag).

%% D
spam(Attr)->
  mnesia:table_info(store, Attr).

% somewhere
  Result = mnesia:activity(async_dirty, fun spam/2, [size], mnesia_frag).