Answer: C
Correct answer: It is entered as an array formula
Ctrl + Shift + Enter enters a formula as an array formula, which Excel shows enclosed in braces - braces that are added by Excel and must never be typed. An array formula operates on whole ranges at once rather than on single cells, which allows calculations that would otherwise need a helper column. =SUM(A1:A10*B1:B10) entered this way multiplies the two ranges element by element and adds the products - the same result as SUMPRODUCT, which does it without the special entry. Array formulas cannot be edited or deleted one cell at a time where they occupy a range; the whole block must be selected. Newer versions of Excel use dynamic arrays, in which a formula returning several values simply spills into the neighbouring cells with no special keystroke at all, and the older form is retained only for compatibility. Functions such as FILTER, SORT and UNIQUE work this way.