Final answer:
The correct answer is option b. Zachary can't be baptized at the church because he's not a member of the church.
Step-by-step explanation:
The reason why Zachary can't be baptized at the church is most likely because he is not a member of the church (Option b). Baptism is a religious sacrament typically performed for members of the church. It signifies initiation into the Christian faith and membership in the church community.
If Zachary is not a member of the church, he may need to meet certain requirements or go through a process of joining the church before he can be baptized. Different churches may have different rules regarding baptism and membership. Being religious (Option a), interested (Option d), or too heavy (Option c) are unlikely reasons for not being able to be baptized at the church.