The correct option is A 1
Out of the three given reactions, (a) and (c) will yield products as shown below.
(a) Mg(s)+CuSO4(aq)→MgSO4(aq)+Cu(s)
(c) Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)
This is because Mg is highly reactive than Cu and hence can be displaced easily by Mg. Similarly, Zn is more reactive than H and thus gets displaced.
However, (b) will not yield any product as Cu is a less reactive metal when compared to Zn. Thus, there will be no such reaction.