The answer is Branded ad
Branded ads are promotional pieces created by advertisers that are designed to look like regular news articles. They can deceive readers into thinking they are reading unbiased news content when, in fact, the content is promotional.
A letter-to-the-editor is a letter sent to a publication about issues of concern from its readers. It is not designed to deceive readers into thinking it is a news article.
A "Dear Abbey" letter is a type of advice column where readers write in with personal problems and receive advice. It is not intended to deceive readers into thinking it is a news article.
Biased material refers to content that shows an unfair preference or prejudice for or against something. While it can be misleading, it is not specifically designed to look like a typical news article.
The answer is Conflict of interest
A conflict of interest occurs when a party has competing interests or loyalties. In this case, NBC might avoid covering the oil spill to protect its relationship with Exxon Mobile, which would be a conflict of interest.
An echo chamber is an environment where a person only encounters information or opinions that reflect and reinforce their own. This is not directly related to the concern of NBC not covering the oil spill.
Native ads are a type of advertising that matches the form and function of the platform on which it appears. This is not directly related to the concern of NBC not covering the oil spill.
Investigative reporting involves in-depth reporting to uncover the truth about a particular subject, often involving wrongdoing. The concern here is not about the lack of investigative reporting but about the potential conflict of interest.