The board of a school district shall admit students from other districts to its schools if:
1. The admission does not create overcrowding; and 2.
a. The board of the sending district has entered into a contract with the board of the admitting district regarding the students' attendance;
b. Tuition will be paid by the parents of the students from the sending district; or c. The grade level required by the students is not offered by the sending district.