Final answer:
In challenging the competence of the evidence presented to the grand jury, the defendant questions the sufficiency, reliability, and credibility of the evidence.
Step-by-step explanation:
When challenging the competence of the evidence presented to the grand jury, the defendant must believe that the evidence is not sufficient to establish probable cause or meet the legal standards required for a conviction. The defendant may argue that the evidence is unreliable, contradictory, or obtained unlawfully. They may also challenge the credibility of the witnesses or the methods used to collect the evidence.