Question 18th - Manhattan 5lb - Ratio Chapter

The ratio of 16 to g is equal to ratio of g to 49.

Quantity A => g

Quantity B => 28

**Issue**

I considered only positive value for g, because in official ETS Math Review, the definition of a ratio is given as follows:

Due to this I had marked answer as C considering g=28. But in answer explanation, negative value has also been considered. Can someone pls help me understand how to proceed on this.

Thanks!