Could someone explain the following to me. I got answers but just wanted to confirm. Help is surely appreciated, thanks!

1)Use the remainder theorem and the factor theorem to determine whether (y-3) is a factor of (y^4 + 2y^2 - 4)

A. The remainder is 0 and, therefore, (y-3) is a factor of (y^4 + 2y^2 - 4)

B. The remainder is 0 and, therefore, (y-3) isn't a factor of (y^4 + 2y^2 - 4)

C. The remainder isn't 0 and, therefore, (y-3) is a factor of (y^4 + 2y^2 - 4)

D. The remainder isn't 0 and, therefore, (y-3) isn't a factor of (y^4 + 2y^2 - 4)

2) Use the remainder theorem and the factor theorem to determine whether (b+4) is a factor of (b^3 +3b^2 - b+12)

A. The remainder is 0 and, therefore, (b+4) is a factor of (b^3 +3b^2 - b+12)

B. The remainder is 0 and, therefore, (b+4) isn't a factor of (b^3 +3b^2 - b+12)

C. The remainder isn't 0 and, therefore, (b+4) is a factor of (b^3 +3b^2 - b+12)

D. The remainder isn't 0 and, therefore, (b+4) isn't a factor of (b^3 +3b^2 - b+12)

3) Use the remainder theorem to determine the remainder the remainder when 3t^2 +5t -7 is divided by t-5 (I don't know what I'm doing but the answer is coming out wrong. I'm doing exactly what the example says)

4) Use the remainder theorem and the factor theorem to determine whether (c+5) is a factor of (c^4 +7c^3 +6c^2 -18c+10)

A. The remainder is 0 and, therefore, (c+5) is a factor of (c^4 +7c^3 +6c^2 -18c+10)

B. The remainder is 0 and, therefore, (c+5) isn't a factor of (c^4 +7c^3 +6c^2 -18c+10)

C. The remainder isn't 0 and, therefore, (c+5) is a factor of (c^4 +7c^3 +6c^2 -18c+10)

D. The remainder isn't 0 and, therefore, (c+5) isn't a factor of (c^4 +7c^3 +6c^2 -18c+10)