Which has infinitely many solutions?
a.) -6.8 +3y + 2.4 = 4.3 - 3y
b.) 1/3y + 2.5 - 2/3y =1.2
c.) 5.1 + 2y + 1.2 = -w +2y + 8.3
d.) 2/5y = 2.3 + 3/2y

The ones that simplify to x=x or c=c where c is a constant
as soon as you have
ax+b=c where a, b, and c are constants (and b≠0 and a≠0), then there is one solution

A. -4.4+3y=4.3-3y
-4.4+6y=4.3
this has one solution

B. -1/3y+2.5=1.2
this has 1 solution

C.
6.3+2y=6.3+2y
2y=2y
y=y
infinite solutions

D. 4/10y=2.3+15/10y
 -11/10y=2.3
1 solution

C is the answer