“活动最多部份”可以翻译为 "the part with the most activities" 或 "the section having the highest number of activities"。
The part with the most activities：简洁明了，直接表达了“活动最多的部分”这一意思。
The section having the highest number of activities：稍微正式一些，使用了“having the highest number of”这一结构来强调活动的数量最多。