The answer is D, location, because you'd have moved spots that could be altered.
BPA, or bisphenol A, is in most plastics and it is toxic to humans because it can bind to the estrogen hormone and greatly alter your body's natural functions from there. It can also bind to your thyroid hormone.
Answer:
a) Step 1:

Step 2:

b) The overall balanced reaction for given process is ;

Explanation:
a)
Galena = 
Lead(II) oxide = 
Sulfur dioxide = 
Step 1:
Roasting the galena in oxygen gas to form lead(II) oxide and sulfur dioxide.
Balanced equation of step 1:
..[1]
Step 2:
Heating the metal oxide with more galena forms the molten metal and more sulfur dioxide.
Balanced equation of step 2:
..[2]
b)
For over all reaction add [1] and [2]. The overall balanced reaction for given process is ;

Explanation:
02 is the correct coefficient for hydrogen gas .