Answer
False
Work Step by Step
According to Definition 3.3.1, if we look at any $n x n$ diagonal matrix $A$, we can see that for $i=j$, minor will be determinal of a diagonal matrix obtained by removing the $i-th$ row and $i-th$ column vectors of A.
The product of diagonal sequence is the determinant of the diagonal matrix, according to Theorem 3.2.1.
We have $M_{ii}=a_{11}a_{12}...a_{i-1}a_{i+1}...a_{nn}$
The statement is false since minor is one number, not a matrix.
