rispondere always takes preposition a
yes in transitive form, but other forms: (I answered in writing) Ho risposto per iscritto
Sorry! It says THE telephone. Why isn't it il telefono?
I got tagged for that also, but then just switched the way I look at rispondere....it will no longer be "answer" in my mind but "respond".
a+il = al
Then who was phone?
I guess it's more like "Who was responding to the telephone?" in english.
italian mother speaker here, "AL telefono" should be correct too.