Which action is least likely to improve market share?

Optimizing labor productivity within plants is least likely to directly impact market share. While this action can enhance efficiency, reduce costs, and improve the overall profitability of a company, it does not directly boost the visibility or attractiveness of products in the marketplace. Market share is typically influenced by factors that increase consumer awareness, availability, and satisfaction with a company's products.

In contrast, boosting product awareness through marketing effectively captures consumer attention and can lead to an increase in sales, helping to grow market share. Expanding distribution channels makes products more accessible to consumers, thus potentially increasing sales volume and market penetration. Increasing customer support services can enhance customer experience and satisfaction, encouraging repeat purchases and positive word-of-mouth, which also contributes to market share growth. Therefore, while optimizing labor productivity is important for operational efficiency, it doesn't have the same immediate and direct effect on expanding market share as the other options do.