Final answer:
The licensee must keep ID card training records mainly for IRS requirements, as they play a vital role in regulatory compliance, taxation, and audit processes.
Step-by-step explanation:
The company licensee must retain ID card training records primarily for B. IRS requirements.
While police might issue one-year licenses for handguns with certain provisions around firearm storage and handling, the IRS is concerned with regulatory compliance and would require thorough record-keeping for tax and audit purposes.
In contrast, options A, C, and D do not directly relate to the IRS's functions or common reasons for maintaining training records long-term.