The right chi-squared critical value for alpha/2=0.01 is 1.647 (98% confidence level) with n-1=8 degrees of freedom left chi-squared value is 20.09 for 1-alpha/2=0.99. Using the formula, (a) is the correct answer:
√((n-1)s²/χ²L)<σ<√((n-1)s²/χ²R, √(8×865²/20.09)<σ<√(8×865²/1.647), $546<σ<$1907.
The confidence level is the interval between the left and right chi-squared values, hence the reason for halving alpha.