(1) infinitive, (2) past tense, (3) present participle, and (4) past participle.
Hence, the option B.
I believe it would refer to intelligence quotient.
Awkward, the first one :)
The anwser to that is Narrator
<span>"So-called anonymous tracking is not very secure—the anonymity is fairly easily broken. Cracking [it]...is a fairly easy engineering feat."
This example maintains the main idea of the passage, keeping its message in tact while eliminating information using ellipses to improve clarity. The addition of "it" also helps make it clearer and more concise. </span>
