"I took three photographs."
Translation:Я сделал три фотографии.
"Снимал" is used for usual, repetitive cases or for indefinite tense. It is better to use "снял" (perfective) for this case, since you don't have a regular situation when you should take three shots of each event and you are talking about one of this event. So, the correct answer would be "я снял три фотографии". And this choice with "снял" is more accurate, than another one in this task, because the last one (with "сделал") is ambiguous.