For a consol (perpetuity) with annual coupon $C$ and yield $y$:

$$P = \frac{C}{y}$$

Here, $C = 3$ and $y = 5\%$, so:

$$P = \frac{3}{0.05} = 60$$

For a perpetuity, the modified duration is:

$$D_{mod} = \frac{1}{y} = \frac{1}{0.05} = 20$$

So A is true.

Why the others are false:

• B: Higher convexity does not guarantee superior performance; return also depends on carry, yield curve shifts, and financing effects.
• C: Duration and convexity generally rise with maturity, but DV01 is not a universal monotonic rule in all settings.
• D: Portfolio convexity is also value-weighted across component bonds, so this statement is false.