In JavaScript, a function or method is "called" or invoked by appending parentheses () to its reference. While the provided options contain multiple syntactical errors (e.g., incorrect object reference Window, incorrect casing sayhello, use of a comma), option B is the only one that includes the invocation parentheses (). This operator is the fundamental syntax for executing a function. The question is likely designed to test the identification of this invocation operator as the key part of a method call.

A. Obj,sayHello;: This option lacks the invocation parentheses (). It is not a valid method call and would be interpreted as a comma operator expression.

1. Mozilla Developer Network (MDN). Functions. The "Calling functions" section demonstrates that invocation requires parentheses. Retrieved from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions#callingfunctions

2. ECMA-262, 14th edition (June 2023). ECMAScript® 2023 Language Specification. Section 13.3.6, "Function Calls," specifies the CallExpression syntax which requires arguments enclosed in parentheses.

3. MIT OpenCourseWare. 6.170 Software Studio, Lecture 10: JavaScript. The course materials distinguish between referencing a function by its name and calling it using parentheses.