Karan is not . . . . . . . . his father.

The sentence compares Karan's mindset to his father's.

We need a phrase that means "similar in mindset".

Let's look at the options:

Option A: as minded as - This option is grammatically correct and commonly used for comparisons. It means Karan's mindset is similar to his father's.

Option B: so minded as - This option is not grammatically correct. "So" is usually used with "that" or another clause, not directly with a comparative structure.

Option C: minded as - This option is incomplete and doesn't make grammatical sense. We need a comparative structure.

Option D: so minded like - This option is also grammatically incorrect. We use "as" for comparisons, not "like".

Therefore, the only grammatically correct and meaningful option is Option A: as minded as.