a$.$ write a sequential C program to reads two integer N x N arrays and perform matrix multiplication of A$*$B and save results in new matrix C$,$ assume both matrices A and B are diagonal matrices, $($i$.$e all elements off the diagonal are zeros$),$ this should be taken in consideration to minimize the loops and coding. N is a defined constant set to $1000.$ Assume matrices A and B have already been initialised.

b$.$ Modify the code using OpenMP directives to parallelize the code using P threads, where P is also a defined constant and N is a multiple of P$.$

c$.$ Finally re$-$write the code to be an MPI program with P processes.

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