Jenny is taking a quiz that asks for the chemical symbols of 20 elements. She remembers 19 of them but cannot remember the symbol for mercury. As she walks home from school, she suddenly remembers that the symbol for mercury is Hg. Jenny's memory problem during the quiz can best be explained in terms of:

too limited long-term memory search          

Explanation:

Long-term memory: In psychology, the term long-term memory is also referred to as LTM, and is defined as one of the stages in the "information processing model" given by Atkinson–Shiffrin in which different informative knowledge is being held indefinitely.

Long-term memory of an individual tends to store and then recall a particular piece of information for future use. If the information present in the long-term memory of a person is not being used for a long time then that information is transferred into the unconscious memory and is difficult to access.

dude you should crop your image so only the question shows. but   can you explain it better