The Market for Smart Phones Has Grown Rapidly Over the Past

The market for smart phones has grown rapidly over the past few years, due in part to the overwhelming success of the Apple iPhone. Following the successful launch of the iPhone in 2007, companies such as Samsung, HTC, and LG have all introduced products to compete with the iPhone. The smart phones introduced to compete with the iPhone would be considered

A) complements to the iPhone.
B) substitutes for the iPhone.
C) inferior goods compared to the iPhone.
D) normal goods compared to the iPhone.