NO.PZ2021030502000017
问题如下：
which of the following statements about Corporate Credit Markets in the time of COVID-19 is incorrect?
选项：
A.Conditions in the corporate credit markets have deteriorated sharply since late February on the back of rising credit and liquidity risks. B.Investment grade bond spreads narrowed, as investors started to focus on a large share of BBB credits that are at risk of downgrades and reduce leverage in this market segment. C.Several central banks rolled out new facilities and expanded existing programs to support issuance and liquidity in corporate debt and commercial paper markets. D.Strains in the risky credit market segments—high-yield bonds, leveraged loans, and private debt—continued to be evident through early April.解释：
B is correct
Investment grade bond spreads widened, as investors started to focus on a large share of BBB credits that are at risk of downgrades and elevated leverage in this market segment.B选项错在两个地方，投资级债券的利差是扩大的，杠杆增加了而不是减少的。
帮忙解释下d选项，没看懂
