Please help

The Cash table below contains seven attributes. Which of those could possibly be foreign keys? (You may select more than one answer. Single click the box with the question mark to produce a check mark for a correct answer and double click the box with the question mark to empty the box for a wrong answer. Any boxes left with a question mark will be automatically graded as incorrect.) Cash Receipt: Remittance Advice # RA-220 RA-278 RA-276 RA-289 Date Amount Customer # Check # Invoice # Cashier # 11/02/2016 2549.90 11/10/2016 11/30/2016 1209.70 11/30/2016 C-12 C-5 C-9 C-28 201 1457 392 2558 S-101 S-108 S-107 S-105 E-13345 E-13347 E-13345 E-13346 699.90 949.95 Amount a cashier # invoice # Customer #