Calculate Cohen's d for t = 2.04 with N = 40 for each of the two groups.

A) .05
B) .23
C) .46
D) .66

Cohen's d is calculated using the formula $d=\frac{t}{\sqrt{N}}$ , where $t$ is the t-value and $N$ is the total sample size. Given $t=2.04$ and $N=40$ (which means 20 per group for two groups), the calculation is $d=\frac{2.04}{\sqrt{40}}$ , which approximates to 0.32. However, since this specific value is not among the options and the correct approach to calculate Cohen's d for two groups with a given t-value and total N would indeed yield a value around this magnitude, it seems there might have been a mistake in the calculation or in the provided options. Among the given options, .32 is not available, and my explanation was based on the standard calculation method. The closest correct approach given the options would be to reconsider the formula or the interpretation of the options provided.