In each question below, two sentences are given with one blank each. Choose the option which contains the word that fits in both sentences, making them grammatically and contextually correct. 1. The barrister's ____ during cross-examination left the witness stumbling over contradictions he had never anticipated. 2. The sheer ____ of the mountain trail intimidated even the most seasoned trekkers in the group.

Sentence 1 — Needs a noun reflecting mental sharpness. ACUITY means keenness of mind, which explains why the barrister's questioning exposed the witness's contradictions. Sentence 2 — Needs a noun describing the trail's intimidating quality. ACUITY also means sharpness in a physical sense — the steep, razor-sharp demanding nature of the trail. Option 1 (Acumen) is limited to business/practical judgment — too narrow for S2. Option 2 (Tenacity) means persistence — fits neither. Option 3 (Severity) loosely fits S2 but fails S1's context of sharp logical questioning. Option 4 (Craft) is weak in both.