A U. S. investor has purchased a tax-exempt 5-year municipal bond at a yield of 3.86 percent which is 100 basis points less than the yield on a 5-year option-free U. S. Treasury. If the investor’s marginal tax rate is 32 percent, then the yield ratio is closest to:()

A. 0.79.

B. 1.26.

C. 3.68.

幼儿6岁左右，最先萌出的恒牙是“第一恒磨牙”，又称（）。