Which line of code should you use?

You are testing the value of the following variablein JavaScript.
var height = “300”;
A block of code must execute if the following conditions are true:
– The height variable is set to 300
– The height variable is of type string
You need to implement the code to run the test.
Which line of code should you use?

A.
if (height == 300)

B.
if (height === “300”)

C.
if (height ! “300”)

D.
if (height != 300)