let me re-write the proposition:
p↔q⊕(¬p↔¬r)∧¬q.
Generally, the number of rows in a truth table depends on the number of Variables. Here we have 3 Variables: p,q and r. Each of them can have either the value of 1 or 0, which gives us 2*2*2 possibilities, or 2³, that is 8 possibilities and 8 rows:
p=0, q=0, r=0
p=0, q=0, r=1
p=0, q=1, r=0
p=0, q=1, r=1
p=1, q=0, r=0
p=1, q=0, r=1
p=1, q=1, r=0
p=1, q=1, r=1
