Matrix M is of order 4×5 and matrix N is of order 4×3. Which statement correctly explains why M−N cannot be performed?
a) Matrix subtraction is allowed only when both matrices are square, which these are not.
b) Their inner dimensions 5 and 4 do not match, so subtraction is impossible.
c) They have the same number of rows but different numbers of columns; thus, their orders differ.
d) Subtraction is invalid because the total numbers of elements 20 and 12 are unequal.