Answer:
The correct option is (a)
Step-by-step explanation:
Trading down is an approach of bringing down product features or its related benefits to reduce the quality so as to meet the consumer price expectations. It could be an effluent product that finds its place with customers if it is available for sale at a reduced price.
The only way to make available such products to customers is by trading them down or reducing its features. Here, BMW makes 1 series available to customers at reduced price by making it smaller. So, the company is clearly following trading down approach.