Answer: e. Laura is brand loyal to the brand of cereal she buys, but visits the same store out of inertia.
Explanation:
From the question, we are informed that Laura often goes to the only grocery store across the street from her apartment building and buys the same brand of cereal every week even though the store sells several different brands of cereal.
The most likely reason for this is that Laura loves that particular brand of cereal she buys maybe due to its packaging, taste, quality etc. So, in this case she is brand loyal to that particular brand of cereal as she won't like to buy or consume any other brand apart from that but she visits the same store out of inertia as its the only store across the street from her apartment building
If there were other stores, she could have gone into them but will still purchase the same brand of cereal.