The correct option is C Saturday
Alida goes to church every two days so, after Sunday she'll go to the church on Tuesday, Thursday and Saturday.
Alida goes to the park every three days so, after Sunday she'll go to the park on Wednesday and Saturday.
Therefore, she'll go to both places on Saturday.
We can use the application of L.C.M here, as we need to know the number which will be divisible by the given numbers.
L.C.M of 2 and 3 = 6
So, she'll go to both places after 6 from Sunday, which is a Saturday.