Which of the following options represents the correct syntax to open a file whose name is contained in the variable filename? cout > filename; ifstream in_file; in_file.open("filename"); O in_file.open(c_str(filename)); O in_file.open(filename.c_str(); O in_file.open(filename); Which of the following is a common pointer error? Setting a pointer variable to a new value Dereferencing a pointer Setting a pointer variable to NULL Using a pointer that has not been initialized Which of the following statements hold true when you want to pass an array to a function? The function cannot make changes to the array. You cannot pass an array to a function. A function always receives the starting address of the array. You have to pass all the values of the array as parameters to the function. Which of the following is the correct way to call the open function for "File.txt" on an of stream object called writestr ? O writestr.open("File.txt") O writestr.open writestr.open("File.txt", "write") o writestr.open("File", ".txt") What is the output of the following code snippet, assuming a correct program surrounds it? struct Point2D { double x; double y; } Point2D p1(2,3); cout x y; x2 y2 Possible runtime error No output, it won't compile O 23