Clearly, there were supposed to be other answer choices to this question.  The major reason that computers were not marketed to homes in the 1950s is that they were too big and too expensive.

During the 1950s, there was no such thing as a personal computer.  All computers were things the size of rooms, if not of whole houses.  For example, ENIAC, the first general-purpose computer, filled a room that was 9 by 15 meters. This would have been completely impractical for home use.

Computers this large were, of course, expensive.  ENIAC cost $500,000 to create in the 1940s.  This computer was still in use until the mid-1950s.

With computers that big and that expensive, there was no way computers could be sold to individual families.