User-125547262 posted
protected -- A class and other its children have access to that member or method
public -- as the name suggests its public hence anyone can access this member or method
partial-- this keyword is used when a class declaration is split up into more than one file.At compile time the compiler combines the declarations into one class
Having said this if this method is inside your page class and its used only in the page_load then private would suffice ( private means only that class has access)