a = peak value of P_{x} = 2/l (i.e., the value of P_{x}
at those x for which sin^{2}() = 1)

The wavelength = the length of 2 humps = l/2 for an n = 4 electron.

Probability = area relative to the whole area under the curve which is 1

The area for the space from x = l/2 to x = (3/4)l = 1/4

Wave function or j = P_{x}^{1/2}
is given in the figure.

Answer is C