Tom simplified an expression in three steps, as shown below: 
 Which is the first incorrect step and why? 
 A). Step 1: all the exponents are increased by 4 
 B). Step 2: the exponents of the same base are added during multiplication 
 C). Step 3: the exponents of the same base are subtracted during division 
 D). Step 3: all the exponents are added during division