% increase in Company A sales.
Let the 2005 sales for company A= X
Let the 2006 sales for company A= Y
$$\frac{y-x}{x}\cdot\frac{100}{1}=\%\ increase$$

Statement 1: In 2005, the sales for company A were 1/4 of the sales of company B.
Let sale of company A in 2005 = xA
Let sale of company B in 2015 = xB
$$Therefore,\ xA=\frac{1}{4}\cdot xB$$
This does not provide us with enable information on the sales for company B in 2005. Hence, Statement ! is INSUFFICIENT.

Statement 2: In 2006, the sales for company A were 3/4 of the sales for company B in 2006. Hence, statement 2 is INSUFFICIENT.
Combining statement 1 and 2 together.
$$Statement\ 1=\ xA=\frac{1}{4}\cdot xB$$
$$Statement\ 2=\ xa=\frac{3}{4}\cdot xb$$
Rewriting the equation, we have
$$\frac{\left(0.75\cdot xb\right)-\left(0.25\cdot xb\right)}{\left(0.25\cdot xb\right)}$$
No information on the values of sales for company B in 2005 and 2016. hence the two statement combined together are INSUFFICIENT
Answer is Option E