<p>Fig --</p>
<p>The screening process should certainly catch problems like I described. But how does it catch them? I believe it is by checking to see that when it appears on an equating section, that the lower scorers are not getting it right at an unexpected rate. But if those lower scorers have been coached to guess C, the screening process will be less likely to catch a flawed problem if it has an answer of A or E. </p>
<p>So I guess if I had to guess randomly on a hard question, I would go with A or E. But, of course, this is all just silliness: no one has to guess randomly on ANY question! Devising clever guessing strategies is, for the most part, a distracting waste of time.</p>