Final answer:
Collective investment funds must be valued at least quarterly under 12 CFR 9.18, with an exception for real estate (a)(2) funds.
Step-by-step explanation:
According to 12 CFR 9.18, collective investment funds must be valued at least quarterly. This regulation is specifically in the context of the valuation of bank-maintained collective investment funds, often known as CIFs or collective trust funds. There is an exception for real estate (a)(2) funds, where valuation may have a different schedule as specified in the written plan governing the fund. Therefore, the correct answer to the student's question is option 2) quarterly, except for real estate (a)(2) funds.