The wrong options are not random. They are your likely mistakes, written down.

Every distractor on a well-written exam is the answer you get by making one specific error. Learn the errors and the options start telling you things.

The design principle

A good multiple choice item has one correct answer and three options that each correspond to a plausible mistake.

That means the options are diagnostic. If you compute an answer and it matches an option exactly, that is weak evidence you are right, because your mistake was probably anticipated.

It also means an option that looks like nothing you would produce is usually filler, and can be eliminated fast.

The recurring distractor patterns

• The undercorrected answer. You applied one derating factor and not the other, and the option is there waiting.
• The wrong column. Ampacity read at 90 degrees when the termination limits you to 75.
• The wrong current. A motor answer computed from the nameplate where the table was wanted, or the reverse.
• The unrounded answer. Correct arithmetic, but you did not round to a standard device rating or up to a real conductor size.
• The right answer to the adjacent question. You computed the primary when it asked for the secondary, or the branch circuit figure when it asked for the feeder.
• The off-by-a-factor answer. Missing the square root of three, or using one-way length instead of round trip.

Six patterns cover most of it. Every one of them is a step skipped rather than a fact unknown.

How to use this while sitting

When your computed answer appears among the options, spend five seconds asking which error would produce each of the others.

If you can account for all three wrong options as specific mistakes, your confidence should go up. If two options look like they came from nowhere, check whether you have misread the question, because you may be answering something it did not ask.

The other kind of wrong answer

Some options are wrong because they state a real rule that does not apply here. Those are the hardest, because they are true sentences.

The tell is usually scope: the rule is real but it applies to dwellings and this is commercial, or it applies to services and this is a feeder.

When two options both look defensible, the question is almost always about which scope you are in.

What this is not

This is not a way to pass without knowing the material, and anyone selling that is selling nothing.

It is a way to convert the material you do know into more marks than it would otherwise produce, and to catch your own slips before you commit to them.