Answer:
B :step 2 she didnt collect all the like terms and calculate
Step-by-step explanation:
first rewrite remove all ( )Parentheses
2nd collect all like terms and calculate
a^4 + 7a -16 -12^a^3 + 5a -3
a^4 + 12a - 19 - 12a^3 ( Like terms are 7a +5a and -16 +-3)
so she skipped the second step
