Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Problem: sandy walked 20 meters towards south. then sandy turned to her left and walked 20 meters. she then turned to her left and walked 20 meters. she then turned to her right and walked 25 meters. what distance is she from the starting point and in which direction ?
Options: a. 35 m east, b. 35 m north, c. 30 m west, d. 45 m west, e. 45 m east
e

Problem: if a train, travelling at a speed of 90 kmph, crosses a pole in 4 sec, then the length of train is ?
Options: a. 281, b. 125, c. 288, d. 100, e. 121
d

Problem: if 5 students are made to sit in a row, then 6 do n ' t have seats. if 12 students are made to sit in a row, then 3 rows are empty. how many students have to sit a row such that each row has equal number of students and all students are seated ?
Options: a. 0, b. 1, c. 4, d. 5, e. 6

e