Final answer:
The only business directly protected by the U.S. Constitution's First Amendment is the press (the news media). Interest group lobbying is related to the rights of petition and assembly but is not solely a business. The press has explicit constitutional recognition and protection, fundamental for maintaining democratic discourse.
Step-by-step explanation:
The business that is directly protected by the U.S. Constitution in the First Amendment is the press (the news media). The First Amendment guarantees freedom of speech, press, assembly, and the right to petition the government. While interest group lobbying is part of the broader range of activities that fall under these freedoms, specifically freedom of petition and assembly, the press is explicitly mentioned and thus enjoys a distinct level of constitutional protection.
Interest groups and their lobbying activities are regulated to some extent, but the First Amendment ensures that they maintain the right to advocate for their causes. However, the press remains the only business distinctly recognized and protected by the Constitution, which allows print media and other forms of news dissemination to operate with considerable freedom, barring libel or slander.
In relation to other freedoms outlined, such as assembly and petition (which impact how interest groups function), the First Amendment has been interpreted by the U.S. Supreme Court to protect "uninhibited, robust, and wide-open" discourse on matters of public concern, ensuring a strong democratic process.