Answer
The firm will adopt Technique 4, as the overall cost of manufacturing product A would be less than that using Techniques 1, 2, or 3.
Work Step by Step
Techniques 1, 2, and 3 required \$35, \$34, and \$35 respectively to produce A.
By adding up all of the resource prices in Technique 4, $(3\times2)+(4\times2)+(2\times6)+(2\times3)$, we get \$32, which is less than cost of all of the other techniques, and thus the rational economic choice.
