Prove the sum of two rational numbers is rational where a, b, c, and d are integers and b and d cannot be zero. Steps Reasons
1. a over b plus c over d Given
2. Multiply to get a common denominator
3. ad plus cb all over bd Simplify
Fill in the missing step in the proof.

Group of answer choices

ac over bd

ad over b plus cb over d

a plus c all over b plus d

ad over bd plus cb over bd