A student is classifying the following contexts that require the use of either permutations or combinations to solve.

Context A:Jenny needs to determine the number of three-letter arrangements of the letters of the word MATH.

Context B:Ross needs to find the number of 4-person committees that can be formed from a class of 20 people.

Context C:Rob needs to determine the number of arrangements of four books as part of a display shelf.

Context D:Deanna needs to determine the number of three digit security codes that can be formed from the digits 0 through 9 where digits cannot be repeated.

For each context, use 1 to indicate that it should be solved using apermutation,and use 2 to indicate that it should be solved using a combination.

Context Ashould be solved using....

Context Bshould be solved using....

Context Cshould be solved using....

Context Dshould be solved using....