For this case what we should do is find the accent of the following word:
Calculadora
The accent of this word in Spanish is not visible.
When the accent is not visible, then it is called a prosodic accent.
The way to know where the accent is, is in the pronunciation of the word.
When the word acquires the strongest sound, then in that vowel is the accent.
For the word "calculadora" the accent is in the syllable:
"do"
Answer:
The stress in the word calculator is:
A.-do-