Which of the following statements is true about product life cycle theory?

Multiple Choice

The theory was developed in the $1960$ s when the U$.$S$.$ was the leader in R&D$.$

The international system of production is becoming too complicated to be explained by a simple version of the product life cycle theory.

It predicts that over time the U$.$S$.$ switches from an exporting country of new products to an importing country.

all of the options