In What Important Way Do Modern Brain Studies Differ from the Studies

In what important way do modern brain studies differ from the studies performed in the early days of cognitive neuroscience?

A) Modern studies allow researchers to examine brain activity in research subjects who have no problems with memory, speech, or learning.
B) Early studies were based on dozens or hundreds of human subjects, but more recent studies focus on only one or two people per study.
C) Early studies focused on the frontal lobe, while more recent studies have concentrated almost exclusively on the temporal lobe.
D) Recent studies examine more subjects but can be significantly less accurate because the subjects have no cognitive deficits.