Chọn câu có chuỗi hội tụ 

\[\mathop \sum \limits_{{\rm{n = }}1}^{ + \infty } \frac{{2012}}{{\sqrt {{\rm{n}} + 1} }}\]

\[\mathop \sum \limits_{{\rm{n}} = 1}^{ + \infty } \frac{{{{\rm{8}}^{\rm{n}}}}}{{{{\rm{9}}^{\rm{n}}}}}\]

\[\mathop \sum \limits_{{\rm{n}} = 1}^{ + \infty } {\left( {1 - \frac{{\rm{1}}}{{\rm{n}}}} \right)^{2012}}\]

\[\mathop \sum \limits_{{\rm{n}} = 1}^{ + \infty } \frac{{{\rm{n(n}} + 1)}}{{4{{\rm{n}}^2} - 1}}\]