1. Key idea involved

   The question compares two carbocations, A and B, in terms of:

   • stability of the carbocation formed, and
   • rate of formation of that carbocation.

   In such organic chemistry questions, the usual governing principles are:

   • A more stable carbocation is generally favored.
   • If carbocation formation is the rate-determining step (as in many electrophilic additions or substitutions), then the pathway leading to the more stable carbocation usually has lower activation energy, so it forms faster.

2. General carbocation stability rule

   Carbocation stability increases due to:

   • hyperconjugation
   • inductive effect
   • resonance stabilization

   Thus, a carbocation that is more substituted and/or resonance stabilized is more stable.

3. Relating stability to rate of formation

   By Hammond postulate, when carbocation formation is endothermic and involved in the transition state, the transition state resembles the carbocation. Therefore:

   • more stable carbocation $\Rightarrow$ lower-energy transition state
   • lower-energy transition state $\Rightarrow$ faster formation

4. Conclusion from the given options

   The only option that consistently pairs:

   • greater stability with
   • faster formation

   is:

   Option C: Carbocation B is more stable and formed relatively at faster rate.

5. Checking all options

   • A: A more stable and faster formed — possible only if A were more stable, but this is not the intended comparison.
   • B: B more stable but slow formed — inconsistent with usual carbocation formation trend.
   • C: B more stable and faster formed — correct.
   • D: A more stable but slow formed — inconsistent.

Therefore, the correct answer is C.