The product of matrix $P$ and $Q$ is equal to a diagonal matrix. If the order of matrix $Q$ is $3 \times 2$, then order of matrix $P$ is:

$2 \times 3$

The correct answer is Option (3) → $2 \times 3$ ##

Given that the order of matrix $Q$ is $3 \times 2$. It means Q has 3 row and 2 columns.

For the product PQ to result in a diagonal matrix, P must have the same nusmber of columns and Q’s row.

Since, Q has 3 row, P must have 3 columns.

Therefore, the order of P is $n \times 3$, where n denotes the number of rows in P.

Then, $n=2$ (As diagonal matrix is a square matrix)

Then the order of $P=2 \times 3$.