The Machine $A_1$ is accepting all strings that ends with $a$ i.e. $L_1 = \{a ,ba,aa, bba,aba, aaa, aba....\}$
The Machine $A_2$ is accepting all strings that starts with $b$ i.e. $L_2 = \{ b, ba, bb, baa, bbb, bab, bba ....\}$
$A.$ $ba$ is a string which is accepted by both $A_1$ and $A_2$
$B.$ $aa$ is a string which is accepted by $A_1$ but not by $A_2$
$C.$ The DFA for $A_1$ is as shown
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