Which deductible type requires the insured to pay a fixed dollar amount out of pocket before insurance responds to any single loss?

Why this is the answer

A straight or flat deductible is the most common deductible structure: a specified dollar amount (e.g., $1,000) is subtracted from each loss payment. If the loss is $4,500 and the deductible is $1,000, the insurer pays $3,500. A percentage deductible calculates the deductible as a fraction of insured value (common for wind/hail in coastal zones). A disappearing deductible shrinks to zero as loss severity increases past a threshold. A calendar-year deductible accumulates across all losses in a policy year until the threshold is met, then the insurer pays 100%.