The is the order in which arithmetic operators are calculated. a. order of signs b. order of values c. order of calculations d. order of operations

The correct answer for this completion exercise is the last option (option d): 
d. order of operations

 When you need to solve and exercise, the order of operations must be the following:

 You must solve:

 1. The parentheses.
 2. The exponents.
 3. Multiplications and Divisions.
 4. Additions and Subtractions.

 It is important to remember that the  Multiplications, Divisions, Additions and Subtractions, must be solved from left to right