Answer:45 choices

Working notes for the above answer is as under

First step is to  select is any from from Ten individuals , so you can have 10 different choices.
Now   you have selected one you can select the second individual  from nine  individuals. So altogether you have  is 90(10*9) choices.
But  w can say that every change to select x as number one, and y as number two , also the situation where you have selected y as number one  and x as second. So when the order of selection is not relevant you have to divide the number of choices by 2 giving 45 different choices.