Which of the following scenarios BEST describes a brand that exhibits "niche" expertise for SEO ranking purposes?

a$.$

An e$-$commerce furniture retailer has at least $10$ pages with unique content addressing specific topics $($e$.$g$.,$ the best furniture sizes for small spaces; how to place furniture to make the most of small rooms$)$ related to a "hub" keyword $($e$.$g$.,$ furnishing small spaces$).$

b$.$

A home repair service lists all $15$ cities it serves in a dropdown menu on its home page.

c$.$

All of these scenarios describe a brand that exhibits "niche" expertise very well.

d$.$

A digital marketing agency tailors social media posts to reflect unique target audience preferences on each social media platform $($e$.$g$.,$ Twitter vs$.$ Instagram$).$