Final answer:
The concept of a g factor implies that intelligence is a single overall ability.
Step-by-step explanation:
The concept of a g factor in intelligence implies that intelligence is a single overall ability (option 1) rather than several specific abilities (option 2). British psychologist Charles Spearman proposed the idea of a general factor, or g, that underlies all cognitive abilities.
This idea is supported by the Cattell-Horn-Carroll (CHC) theory of cognitive abilities, which arranges abilities in a hierarchy with general abilities at the top and specific abilities at the bottom.
Therefore, the correct answer to the question is option 1) is a single overall ability.