According to the regulation of the pyramid series, the formula $$1+2+3+4+5+6+5+4+3+2+1=$$． 
Overseas Competition->Knowledge Point->Calculation Modules->Sequences and Number Tables
``Pyramid series''$$1+2+3+4+\cdots +\left( n-1 \right)+n+\left( n-1 \right)+\cdots +3+2+1$$  $$={{n}^{2}}$$．  So the answer is $$\text{A}$$． 