The available options are:
A.  normal behavior for children that age. 
B.  a sign of pending food allergies. 
C a major risk factor for nutrient deficiencies.
D.  good indicator the child will become a picky eater.
Answer:
D. Normal behavior for children at that age.
Explanation:
Food jag is a term that explains a condition in which a child often prefers to eat just one food over a given period of time. For instance, a child may only want to eat bread for every meal.
However, Food jags is a common occurrence in children, and it is considered not to be a symptoms of serious medical issues or psychological problems. Thus, that kind of eating habits are a normal part of childhood development. 
It is often considered to be a way for children to assert their independence and to exercise level of control over how they live their daily lives.
Hence, in this case, Short-term food jags such as this during the toddler/preschool time period is: NORMAL BEHAVIOR FOR CHILDREN THAT AGE.