The specification for the pull strength of a wire that connects an integrated circuit to its frame is 10 g or more. Units made with aluminum wire have a defect rate of 10%. A redesigned manufacturing process, involving the use of gold wire, is being investigated. The goal is to reduce the rate of defects to 5% or less. Out of the first 100 units manufactured with gold wire, only 4 are defective. True or false:

a. Since only 4% of the 100 units were defective, we can conclude that the goal has been reached.

b. Although the sample percentage is under 5%, this may represent sampling variation, so the goal may not yet be reached.

c. There is no use in testing the new process, because no matter what the result is, it could just be due to sampling variation.

d. If we sample a large enough number of units, and if the percentage of defective units is far enough below 5%, then it is reasonable to conclude that the goal has been reached.