Starting with B2, if 3 is true then one has a chain of consequences (as following in red):
B2 : 3, D2 : 5, E3 : 7, E5 : 8, A5 : 5, one can thus exclude 5 from A4
If it is 2 wich is true in B2, then we have (as following in green):
B2 : 2, B4 : 5 and 5 can be excluded from A4.
In any case, 5 can be excluded from A4.