Studying Sensory Functioning in Infants Had Posed Significant Problems for Researchers

Studying sensory functioning in infants had posed significant problems for researchers until they realized

A) that they could measure sensory function directly.
B) that different states could be triggered by different levels of sensory stimulation.
C) that psychophysiological functions are effective in probing infants' sensory capacities.
D) that comparable standards exist between adult and infant perceptions.