In an experiment, encouraged people performed a puzzle with 90% accuracy, M ₁ = .90. The not-encouraged group performed a puzzle with 70% accuracy, M ₂ = .70. The value of r² was calculated as 0.20. Which is true below?

a) The proportion of variance in puzzle performance accounted for by assignment to the encouraged or not-encouraged group was 20%.

b) The proportion of variance in assignment to the encouraged or not-encouraged group accounted for by puzzle performance was 20%.