If ABCD is a parallelogram, then it means line BC = AD.
Similarly, line BA = CD
Therefore;
[tex]\begin{gathered} BC=AD \\ 2x=x+5 \\ \text{Subtract x from both sides} \\ 2x-x=x-x+5 \\ x=5 \\ \text{If x=5, and line AD=x+5, then} \\ AD=x+5 \\ AD=5+5 \\ AD=10 \end{gathered}[/tex]The length of AD is 10 units
The answer is option B