If Simple Reaction Time Takes an Average of 0

Multiple Choice

If simple reaction time takes an average of 0.17 seconds and discrimination reaction time takes an average of 0.26 seconds, then according to Donders' method, how long does the mental event of discrimination take?

A) 0) 43 seconds
B) 0) 26 seconds
C) 0) 09 seconds
D) 0) 20 seconds