💡 Detailed Explanation
"～ものがある" is used to express the speaker's impression or feeling that something "feels a certain way" or "has a certain quality." Here, it means "I feel deeply moved by the sight of the children trying their best." The other choices do not fit the context: "～ことになっている" (it's a rule/plan), "～わけにはいかない" (can't do something for social/moral reasons), and "～にほかならない" (it is nothing other than..., a strong assertion).