Final answer:
For between-subjects experiments with three conditions measuring performance on a ratio scale variable, the correct statistical test is C) Analysis of Variance (ANOVA), given it compares the means of more than two independent groups.
Step-by-step explanation:
If a researcher conducted a between-subjects experiment with 3 conditions and measured subjects' performances on a ratio scale variable to measure the differences between the conditions, the correct statistical test to compute would be C) Analysis of Variance (ANOVA). An ANOVA allows comparison of the means of more than two independent groups and is appropriate here because there are three conditions (levels of the categorical independent variable). One-way ANOVA is suitable if all populations are normally distributed, have equal standard deviations, and samples are randomly and independently selected from each population. Given that each sample has a different standard deviation, it suggests that further testing for equal variances might be necessary before proceeding. However, ANOVA is still the initial applicable choice among the given options for testing if several population means are equal.