What is the ratio of the number of mobile phones sold of company B during July to those sold during December of the same company?

Answer: Option C

Number of mobile phones sold by B during July
$$\begin{array}{rl}& =45000\times \frac{17}{100}\times \frac{7}{15}\\ & =3570\end{array}$$
Number of mobile phones sold by B during December
$$\begin{array}{rl}& =45000\times \frac{16}{100}\times \frac{9}{16}\\ & =4050\\ & \therefore \text{Required ratio}\\ & =\frac{3570}{4050}\\ & =\frac{119}{135}\\ & =119:135\end{array}$$