Official solution
\[A \to (B \to A)\]
\[ \Rightarrow A \to ( \sim B \vee A)\]
\[ \Rightarrow \, \sim A \vee ( \sim B \vee A)\]
\[ \Rightarrow \, \sim B \vee ( \sim A \vee A)\]
\[ \Rightarrow \, \sim B \vee t\]
= t (tantology)
From options :
(B) \[A \to (A \vee B)\]
\[ \Rightarrow \, \sim A \vee (A \vee B)\]
\[ \Rightarrow ( \sim A \vee A) \vee B\]
\[ \Rightarrow t \vee B\]
\[ \Rightarrow t\]