问题如下：
What is the impact on the bond price-yield curve if, all other factors held constant, the maturity of a zero-coupon bond increases? The pricing curve becomes:
选项：
A.less concave.
B.more concave.
C.less convex.
D.more convex.
解释：
D is correct. As the maturity of a bond increases, the price-yield relationship becomes more convex.
请教下，这道题考的是不是FULL PRICE、D+C、D和利率变化的那个图
