Explanation

Since the analysts found that the company’s statistics underestimated the potential for accidents, the answer to Blank (iii) must reflect the inaccuracy or inapplicability of those statistics. “Deceptive” is the only choice that does so. Blank (i) must then be answered with a choice that reflects the more positive view of accident prevention that deceptive statistics might provide. “Frustrated” efforts would imply the opposite, and while “innovative” has positive connotations, the passage is concerned with the effectiveness of safety measures rather than with their novelty.
Thus “successful” is the correct choice. Finally, the word for Blank (ii) describes something related to potentially dangerous incidents that would indicate if it were to decline. If “impediments to” or “attention to” such incidents were to decline, that would likely have the opposite implication. However, fewer such incidents would presumably be a sign of improved safety; thus “frequency of” is the correct response. Thus the correct answer is successful (Choice B), frequency of (Choice D), and deceptive (Choice G).
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