问题如下：
The risk that a bond’s creditworthiness declines is best described by:
选项：
A.credit migration risk.
B.market liquidity risk.
C.spread widening risk.
解释：
A is correct.
Credit migration risk or downgrade risk refers to the risk that a bond issuer’s creditworthiness may deteriorate or migrate lower. The result is that investors view the risk of default to be higher, causing the spread on the issuer’s bonds to widen.
请问A是什么意思？
