B. monopoly
Since that company bas almost all of the long phone service, it means that the company is a monopoly because it has exclusive control over phone service in general. There's little competition, so the company can do almost anything it wants to (even raise prices they charge their customers).
An income tax is a tax imposed on individuals or entities (taxpayers) that varies with the income or profits (taxable income) of the taxpayer. Details vary widely by jurisdiction, hope this helps :)