Final answer:
The direct materials yield variance is not a sales-related variance; it measures the efficiency of material usage during production, unlike sales, market-size, and market-share variances which are related to sales performance.
Step-by-step explanation:
The option that is not a sales-related variance is the direct materials yield variance. Sales variances such as market-size variance, sales-quantity variance, and market-share variance all relate to the sales performance and market conditions affecting the sales revenue of a company. On the other hand, the direct materials yield variance is associated with the production process, specifically measuring the efficiency of using materials in producing goods.