Which of the following is NOT a possible order of a matrix with 24 elements?

Explanation

1. 01

   A matrix of order $m \times n$ has $mn$ elements, so every possible order here has $mn = 24$.

2. 02

   $3 \times 8$, $6 \times 4$ and $2 \times 12$ all give 24, but $4 \times 5 = 20$.