If \[(1+i)(1+2i)(1+3i).....(1+ni)=a+ib\], then2.5.10....\[(1+{{n}^{2}})\]is equal to [Karnataka CET 2002; Kerala (Engg.) 2002]

If \[(1+i)(1+2i)(1+3i).....(1+ni)=a+ib\], then2.5.10....\[(1+{{n}^{2}}

1.	If \[(1+i)(1+2i)(1+3i).....(1+ni)=a+ib\], then2.5.10....\[(1+{{n}^{2}})\]is equal to [Karnataka CET 2002; Kerala (Engg.) 2002]
A.	\[{{a}^{2}}-{{b}^{2}}\]
B.	\[{{a}^{2}}+{{b}^{2}}\]
C.	\[\sqrt{{{a}^{2}}+{{b}^{2}}}\]
D.	\[\sqrt{{{a}^{2}}-{{b}^{2}}}\]
Answer» C. \[\sqrt{{{a}^{2}}+{{b}^{2}}}\]