People who have difficulty remembering recently learned materials because of similar information learned earlier in life are demonstrating the phenomenon of

Proactive interference

Explanation:

Proactive interference is a memory disorder this occurs when the old memories of a person restrain the capacity of the brain to retain the new memories. Thus no new information can be retain in the brain. This may happen when the memories are similar. For example, finding difficulty in remembering the new and old phone numbers.

The given situation is an example of proactive interference as the people may find difficult to learn and remember the recently learned materials as the similar information was also learned in the past.

i think your answer is c. measurement system in which the medication dosage was calculated.