The correct option is B 21st December, 4
Detailed step by step solution:
The first Tuesday of December is on 7th December.
The second Tuesday of December is on 14th December.
The third Tuesday of December is on 21st December.
Tuesdays fall on 7th,14th,21st, and 28th of December.
Therefore, there are 4 Tuesdays in the month of December.