On Sheet3 Cell A1, type the row number that you want to copy from Sheet1. The formulas below will copy that row

Copy Sheet1 row n, column A
=INDIRECT("Sheet1!A" & A1)

Copy Sheet1 row n, column B
=INDIRECT("Sheet1!B" & A1)

Copy Sheet1 row n, column C
=INDIRECT("Sheet1!C" & A1)


Excel INDIRECT Function Guide