Final answer:
The journalist should use the source and describe them as "a company executive who asked to remain anonymous" to maintain the source's anonymity and protect them while providing context to the reader.
Step-by-step explanation:
In the given scenario where a company executive wishes to remain anonymous due to fear of retribution by the company president, the journalist should use this source with caution. Given the potential for retribution and considering the guidance from reporter's privilege, the journalist should opt for a descriptor that keeps the source adequately anonymous. Following the options provided, the most appropriate descriptor to use while maintaining sufficient detail about the source's proximity to the information would be "a company executive who asked to remain anonymous." This descriptor provides context without directly revealing the source's identity, thereby aligning with the principle of protecting the source as well as the integrity of the journalistic process.