Answer:
Option C
Explanation:
Average production of Company B from 2006 to 2011
= $\frac{1}{6}\times\left(\frac{4}{5}\times750\right)$
$+\left(\frac{7}{8}\times800\right)+\left(\frac{4}{3}\times600\right)+$
$\left(\frac{12}{11}\times550\right)+\left(\frac{13}{14}\times700\right)+$
$\left(\frac{14}{13}\times650\right)$
= $\frac{1}{6}\times\left[600+700 +800 + 600 + 650 + 700\right]$ tonnes
= 675 tonnes