Which logarithmic graph can be used to approximate the value of y in the equation 2y=5

The equation   2y=5   is not correct; it is neither logarithmic nor exponential.  Fix this by denoting exponentiation with the symbol "^":  the equation 2^y=5 

You haven't shared the graphs mentioned in your problem statement.  However,  this   2^y = 5 can be solved for y, as follows:

ln is the natural log operator.

ln 2^y = ln 5, or   y(ln 2) = ln 5.  Solving for y,   y = (ln 5) / (ln 2).  You could evaluate these logs on a calculator.  If you had the correct graph in front of you, you could draw a horiz. line thru y = 5 and estimate the value of the x-coordinate of the point where the expo. graph and the line y=5 intersect.