gwd31-11，期待高手指教
11: Cash flows to stock and bond mutual funds have gained strength in the last two months, but fund managers have not been eager to invest the new money, instead of preferring to raise the cash levels in their portfolios at the highest level in six months (?).
A: have not been eager to invest the new money, instead of preferring to raise the cash levels in their portfolios at
B: have not been eager to invest the new money, instead preferring to raise the cash levels in their portfolios to
C: have not been eager at investing the new money, instead of preferring to raise the cash levels in thief portfolios to
D: were not eager to invest the new money, instead of preferring to raise the cash levels the cash levels in their portfolios at
E: were not eager at investing the new money, instead preferring to raise the cash levels in their portfolios to
是不是选完成时比过去时好，这样和前一个分句的完成时保持平行；另外到底是raise to 对呢还是at higher lever对呢？举棋不定，请NN们帮忙啊！！
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