Study passage context: Researchers have identified a gene associated with preference for sweet foods. Experiments with mice suggest that a sweet-taste receptor signals the brain when sweetness is detected, and a similar gene exists in humans. A tendency toward a 'sweet tooth' can therefore run in families, although people can gradually become satisfied with less sugar. Scientists caution against switching the gene off through therapy because naturally sweet foods provide energy and some sugar is needed in the diet. The discovery may instead help in developing better artificial sweeteners. Adapted CTET source question 125: According to doctors, sweet foods are :

1. dangerous
2. energy boosters
3. poisonous
4. deactivated genes