B.
until - until he comes for example ( time before someone comes or something is happened)
Meanwhile - during a period or an action where another thing is happening (at that time)
Later - after some period - two months later ( after passing of some amount of time
Answer:
All the language specialist students were taken by the communication skills lecturer to the language laboratory for prscticals last week.
It is closest to 1/2 because 1/2 of 16/16 is 8/16