In this task, you need to provide the correct option for a given problem on probability from the provided options.

Problem: a letter lock consists of 3 rings each marked with 6 different letters . the number of distinct unsuccessful attempts to open the lock is at the most - . 
Options: a ) 216 , b ) 243 , c ) 215 , d ) 729 , e ) 728
c

Problem: how many different ways can 2 students be seated in a row of 6 desks , so that there is always at least one empty desk between the students ? 
Options: a ) 2 , b ) 3 , c ) 4 , d ) 20 , e ) 12
d

Problem: jane and thomas are among the 7 people from which a committee of 3 people is to be selected . how many different possible committees of 3 people can be selected from these 7 people if at least one of either jane or thomas is to be selected ? 
Options: a ) 20 , b ) 25 , c ) 30 , d ) 35 , e ) 40

b