The correct answer is C) Religious activity in public schools is a dangerous violation of the separation of church and state.
The Engel vs. Vitale case dealt with a New York public school that required students to say a prayer at the beginning of school. In this prayer, students had to acknowledge the existence of God. Praising God in this manner was not taken well by some parents, who sued the school.
After going through the lower level courts, this case finally reached the Supreme Court in 1962. In the final decision, it was stated that a mandatory school prayer was a clear violation of the separation of church and state along with the establishment clasue.