What number makes 3 and 71 divisible by 9?

3 only

7 only

1 only

1, 4, and 7

do you mean which digit is added to 371 so that it is divisible by 3

test for 3, sum of digits divisible by 3

3 + 7 + 1 = 11

if you add 3, 11 + 3 = 14 not divisible by 3

if you add 7, 11 + 7 = 18 divisible by 3

if you add 1, 11 + 1 = 12 divisible by 3

if you add 1, 4, 7 divisible by 3