Kodak announced that it would no longer produce 35 millimeter film cameras, but would manufacture digital cameras exclusively. Sales of digital cameras have grown steadily and have far outpaced the sale of 35 mm cameras in recent years, even among professional photographers. Kodak's decision indicates that 35 mm cameras are probably in the ________ stage of the product life cycle.
A. Market introduction
B. Market growth
C. Sales decline
D. Market maturity
Answer: C. Sales decline