Sol. Let A = ⇒ det = a 1 (b 2 c 3 – c 2 b 3 ) – a 2 (b 1 c 3 – c 1 b 3 ) + a 3 (b 1 c 2 – c 1 b 2 )

= a 1 b 2 c 3 – a 1 c 2 b 3 + a 2 c 1 b 3 – a 2 b 1 c 3 + a 3 b 1 c 2 – a 3 c 1 b 2

if any of the terms is non-zero, then det will be non-zero and all the element of that term will be unity

Now there are 6 elements remaining out of which any one can be unity.

Hence number of non-singular matrices = ×

Hence correct option is

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