Final answer:
Product diversity is caused by differences in product size, product complexity, setup time, and size of batches.
Step-by-step explanation:
The statement that is true about product diversity is option a: Product diversity is caused by differences in product size, product complexity, setup time, and size of batches. Product diversity refers to the variety of products or product features offered by a firm. It can be caused by differences in product size, complexity, setup time, and size of production batches. For example, if a company produces both large and small-sized products, complex and simple products, and has different setup times and batch sizes for each product, it can be said to have a high level of product diversity.