Final answer:
The slope of the line in a graph of the photoelectric effect represents Planck's constant, which is 6.626 × 10^-34 J.s, none of the given options is correct.
Step-by-step explanation:
The graph plotting kinetic energy of emitted electrons against the frequency of incident radiation shows a straight line, indicating a linear relationship between these two variables. The slope of this straight line corresponds to Planck's constant, denoted by h. Considering Planck's constant value is 6.626 × 10-34 J.s, the correct answer to the question is none of the given options. The slope of the line in a photoelectric effect experiment graph, which represents Planck's constant, does not match any of the provided values.