Question

what is required to correctly identify a location on the coordinate plane? an ordered pair; two separate numbers without order; a single number; a letter

Explanation:

A coordinate plane uses two axes (x and y), and a specific location is defined by an ordered pair $(x,y)$ where the order (x first, then y) determines the exact position relative to the axes. Unordered numbers, a single number, or a letter cannot uniquely identify a point on the 2D coordinate plane.

Answer:

A. An ordered pair