The equation and reprsent 

a) 
Two pairs of perpendicular straight lines 
b) 
Two pairs of parallel straight lines 
c) 
Two pairs of straight lines which are equally inclined to each other 
d) 
None of these 
The equation and reprsent 

a) 
Two pairs of perpendicular straight lines 
b) 
Two pairs of parallel straight lines 
c) 
Two pairs of straight lines which are equally inclined to each other 
d) 
None of these 
(c)
The given equations are
(i)
and (ii)
The equation of the bisectors of the angles between the lines represented by (i) is
or
which is same as equation of the bisectors of angles between the line pair (ii). Thus, two lines pairs are equally inclined to each other