D选项可以解释一下吗？

问题如下：

In a surprise monetary policy action on August 10, 2015, the People’s Bank of China cut its daily currency reference rate against the USD, resulting in a large devaluation of the CNY versus the USD. Immediately after the announcement, the CRO of CMM Bank (CMM), an international bank with headquarters in Shanghai, began evaluating the impact of this and other events on the bank’s position.

CMM had outstanding long-term debt denominated in USD and deposits denominated in CNY. A significant portion of CMM’s lending portfolio was also denominated in CNY and consisted largely of loans and lines of credit to Chinese manufacturers who were heavily dependent on imported raw materials. Other loans to non-Chinese firms with exposure to China were denominated in USD. The bank’s portfolio investments included CNY denominated Chinese Treasury securities and other sovereign debt.

A portion of CMM’s retail customer base had invested on margin in the Chinese equity markets. Over the next few weeks, local stock markets experienced declines in share prices. Many of CMM’s larger retail depositors experienced margin calls and had begun to draw down demand deposits to meet them. Offsetting these outflows, however, were increases in the 3-month, 6-month and 9-month term deposit balances at CMM of several large corporate customers. The result was that CMM’s overall net deposit flow had been approximately zero.

As a result of credit developments elsewhere in the world, several of CMM’s sovereign debt holdings were downgraded, some from AA to A and some from A to BBB. One of the noticeable outcomes was that the bid-ask spreads on many of the sovereign bonds held and traded by CMM widened. Despite these developments, CMM’s sovereign debt portfolio remained exclusively investment grade with a weighted average rating of A+.

CMM’s CRO was concerned about the bank’s liquidity position and decided to review the impact of the devaluation and other capital market events on its net stable funding ratio (NSFR). Ignoring any changes in the market value of CMM’s sovereign debt holdings, which of the following is correct?

选项：

The NSFR will not be impacted by the sovereign credit rating changes because the overall sovereign debt portfolio remains investment grade

The NSFR will be reduced by the sovereign credit rating changes but this effect can be offset by selling A-rated sovereign debt and investing the proceeds in gold

The NSFR will not be impacted by the change in demand deposits because the bank’s overall deposit level is unchanged

The NSFR will be reduced by the change in demand deposits but this effect can be offset by issuing common stock

解释：

The shift in the demand deposit base from retail demand deposits to wholesale demand deposits with terms less than one year would reduce the NSFR. The change in retail deposit behavior would likely cause a shifting of demand deposit classification from “stable” to “less stable” also reducing the NSFR. The downward sovereign credit migration would increase the RSF applied to these bonds and reduce the NSFR. The issuance of common stock, which should be classified as Tier 1 capital, would increase the NSFR.