Answer:
d. fullName="Harris, Ray"
Explanation:
// here we define two variables firstName="Ray" and lastName= "Harris"
var firstName = "Ray", lastName = "Harris";
// then we create another variable fullName and assign it the value stored in variabl lastName that is "Harris"
var fullName = lastName;
// then we added a coma and space. At this point fullName= Harris,
fullName += ", ";
// then we added firstName to the variable fullName. At this point fullName=Harris, Roy
fullName += firstName;
Note: the += operator means that add the variable on the left by an amount on the right
a+= b; or a = a + b; both mean same