Juana, now a toddler, was born with a short 5-HTTLPR allele. Which environment would increase the likelihood of her exhibiting behavioral inhibition?
a. A stressful childhood environment with limited maternal or social support
b. Birth order and family composition; if she is the youngest child with two or three siblings
c. Having a family that encourages independence and achievement
d. A home, school, and community offering substantial enrichment opportunities