Telephone Numbers Are Exactly Seven Digits Long,likely Due to Recognition

Multiple Choice

Telephone numbers are exactly seven digits long,likely due to recognition of

A) the limited duration and span of sensory memory.
B) the capacity of both echoic and iconic memory being restricted to about seven digits.
C) our short-term memory capacity being restrained to the magic number.
D) serial transfer of information from short-term to long-term memory.