Jenny has an iq in the average range. however, at school she is doing very poorly. she has consistently scored at two or more grade levels below the grade she is actually in. from this, a diagnostician would hypothesize that jenny most likely

Learning disability

Explanation:

Learning disability is a neurological based process problem. In this disorder, the child has a problem in reading, writing, or mathematical. In learning disabilities, child distracted by higher-order disabilities such as the organization of things, memory, attention, concentration, planning, etc. Learning disability impact a person's academic as well as relations with parents, peers, friends.  

We should not be confused with learning problems that occur due to some other reason such as visual, hearing disability. People who have a learning disability have average and above-average intelligence.  

Thus Janny is suffering from learning disability  

in about winter like late november to january

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer