Carbocations only have 6 valence electrons, and so are really unstable. Carbons can share some of their electron density with neighboring carbocations. This is called induction. Induction gives those carbocations more electron density and makes them closer to a neutral charge, and therefore more stable.

Why carbocation is most stable?

Explanation: The more stable the carbocation, the lower the activation energy for reaching that intermediate will be. The more substituted a carbocation is, the more stable it is. The carbocation bonded to three alkanes (tertiary carbocation) is the most stable, and thus the correct answer.

Which carbocation is more stable than?

What this means is that, in general, more substituted carbocations are more stable: a tert-butyl carbocation, for example, is more stable than an isopropyl carbocation. Primary carbocations are highly unstable and not often observed as reaction intermediates; methyl carbocations are even less stable.