Which of the following is NOT one of the reasons for why baby videos seem to have no benefit for infants' word learning?

a. Videos for infants are poorly designed.
b. Videos for infants are insufficient to support language processing and are developmentally inappropriate.
c. Infants 12 to 18 months of age have limited understanding of relationships between real objects and their depictions in photographs and videos.
d. Infants 12 to 18 months of age spend very little time watching videos.

d