Complex sentence: Any student (5th grade or older) can apply to travel on a program, but some parents have complained that the program's marketing makes it appear that their child was exclusively selected or nominated to participate.
Split into simpler sentences: Any student (5th grade or older) can apply to travel on a program. The nomination process is open to any applicant, but some parents have complained that the program's marketing makes it appear that their child was exclusively selected or nominated to participate.