# Which is more stable out of the given carbocation?

Which is more stable?

1. $$\ce{^+C(CH3)3}$$
2. $$\ce{^+C(CD3)3}$$

I have read in Solomon's and Fryhle that the +I effect of D is more than that of H but here in this problem it is given that $$\ce{(CH3)3C+}$$ is more stable.

How is this possible? Since, deuterium enriches the electron density over the central carbon resulting in the diminishing of a positive charge eventually making the second structure more stable.

Second explanation can be on the basis of hyperconjugation which says that $$\ce{-CH3}$$ is better in showing hyperconjugation than $$\ce{-CD3}$$, but why is this so?

$\ce{C-D}$ bonds are stronger. Hyperconjugation is thus more easily seen with hydrogen rather than deuterium.
To see why $\ce{C-D}$ bonds are stronger.