When Solving Basic Addition Problems, 5-Year-Old Sid Sometimes Counts on His

Multiple Choice

When solving basic addition problems, 5-year-old Sid sometimes counts on his fingers, sometimes starts with the lowest digit, or sometimes starts with the highest digit. According to Siegler's model of strategy choice,

A) Sid has problems with cognitive self-regulation.
B) Sid has a control deficiency.
C) Sid is not yet skilled at cognitive inhibition.
D) Sid's variability in strategy use is adaptive.