Which type of forecast uses the expected number of guests to determine purchasing needs?

The choice of customer count as the correct answer is based on its specific focus on estimating the number of guests expected to visit a restaurant or service establishment. This number is crucial for planning purposes because it directly influences the quantity of food and supplies that need to be purchased. By knowing the anticipated customer count, businesses can align their ordering and inventory management to meet expected demand, minimizing waste and ensuring that they have enough products on hand to satisfy customers.

In contrast, the other options address different aspects of forecasting. A sales forecast generally evaluates projected sales revenue based on various market factors, rather than solely focusing on the number of guests. Market trend analysis is broader and examines overall industry trends and consumer behavior to predict future market conditions, which does not directly relate to specific guest counts. An inventory prediction typically involves analyzing stock levels and usage rates rather than deriving figures from the expected number of guests. Therefore, customer count is the most relevant choice for determining purchasing needs based solely on expected guest numbers.