At what points is the following function continuous? f(x)equals left brace Start 3 By 2 Matrix 1st Row 1st Column StartFraction x cubed minus 729 Over x squared minus 81 EndFraction comma 2nd Column x not equals 9 comma x not equals minus 9 2nd Row 1st Column 13.5 comma 2nd Column x equals 9 3rd Row 1st Column 8 comma 2nd Column x equals negative 9 EndMatrix Question content area bottom Part 1 Choose the correct answer below and, if necessary, fill in the answer box to complete your choice. A. All real numbers except at xequals enter your response here (Use a comma to separate answers as needed.) B. Only at xequals enter your response here (Use a comma to separate answers as needed.) C. All real numbers x