What is the root cause of alterations in manufacturing?

Directions: Read the following passage and answer the question on the basis of the content of the passage.
Manufacturing industries are a vital component of all modern economies and all of them require employees who are skilled - in and knowledgeable about - manufacturing processes. Manufacturing is undergoing major transformation due to the unforeseen challenges arising from the current trend of miniaturisation, the emergence of new materials and the growing interaction between biologists and engineers to learn more from nature and living objects. Traditionally, a "top-down" approach has been used in manufacturing. Recently, “bottom-up" approaches have begun for manufacturing today's highly complex products. For small to mid-size manufacturers, a well constructed manufacturing process that maximises the capabilities of your tools, parts and available labour is an essential part of an efficient go-to-market strategy.