I absolutely love Shakespeare so i know for a fact the answer is d with no doubt about it.
The given clause "when the water boils" is an example of a subordinate clause. It is a subordinate clause because it begins with the subordinate conjunction "when". The next clause which is "[You] add the eggs" is the independent clause.
An allusion is a figure of speech that refers to some other written work, time in history, cultural reference, or something most people would understand. For example, if I were to mention an “Achille’s heel” in an essay, anyone would know I was alluding to Homer to mean a deadly flaw.