c

问题如下：

For periods beginning on or after 1 January 2011, firms must not value portfolios:

选项：

when objective, observable market prices are unavailable.

more frequently than required by the composite-specific valuation policy.

as of the last business day of the month unless it is the calendar month-end.

解释：

B is correct.

Provision 1.1.A.3.c states that portfolios must be valued "no more frequently than required by the valuation policy." The definition of fair value includes the statement, "In the absence of an objective, observable, unadjusted quoted market price for an identical investment in an active market on the measurement date, the valuation must represent the firm’s best estimate of the market value." Provision 1.1.A.4 states, "For periods beginning on or after 1 January 2010, firms must value portfolios as of the calendar month end or the last business day of the month." (See Section 3.2 of the reading.)