How to get same type of data in same line in PL/SQL.?

Question

Suppose we have a table of two column like:

'A',  '12'
'B',  '34'
'B',  '45'
'B',  '67'
'C',  '89'
'C',  '98'
'D',  '43'

Now I want a output shows like:

'A', '12'
'B','34','45', '67'
'C', '89', '98'
'D', '43'

So, what query I have to write for that...??