Evaluate (7+2+3)(7+6)(12-3-4): Multi-Parentheses Multiplication

Let's simplify this expression while following the order of operations which states that exponents come before multiplication and division, which come before addition and subtraction, and that parentheses come before all of these,

therefore we'll start by simplifying the expressions in parentheses first:
$(7+2+3)(7+6)(12-3-4)=\\ 12\cdot13\cdot5$

Now we'll calculate the multiplication result step by step from left to right:

$12\cdot13\cdot5 =\\ 156\cdot5 =\\ 780$

Note that since the commutative property of multiplication applies to the expression we simplified above between all terms, the order of operations in this calculation doesn't matter (it's not necessary to perform the left multiplication first etc. as we did), however it is recommended to practice performing operations from left to right since this is the natural order of arithmetic operations (in the absence of parentheses, or other preceding arithmetic operations according to the order of operations mentioned at the beginning of this solution)

Therefore the correct answer is answer C.