Which of the Following Is an Example of a Strain

Which of the following is an example of a strain?

A) Sylvia leaves her waitressing shift early many days in a row as a result of low customer turnout.
B) Amrita develops insomnia while trying meet the deadline to sequencing a new gene.
C) Dario clocks in late to his retail sales job after a night of partying.
D) Vandaya works a second job to save up money for college.
E) Ahmed sits alone on his lunch hour and reads a book.