Option Explicit cannot define?

I have problem to declare option explicit in .aspx file. Before this ive try to write [Imports Option Explicit Off] in my code behind. Its OK. But when Ive try to change the code on .aspx files (i write in .aspx file like this [<%@dotnet.itags.org. Option Explicit Off %>, its cannot define word Option. How to declare the word in .aspx fileJust declare
explicit = true