A Study Was Conducted to Investigate the Effect of an Intervention

Multiple Choice

A study was conducted to investigate the effect of an intervention protocol on IQ tests.Nine randomly selected students were tested. $$\begin{array} { l c } \text { Before } & \text { After } \\100 & 106 \\111 & 112 \\93 & 95 \\92 & 90 \\99 & 107 \\85 & 100 \\117 & 126 \\110 & 105 \\98 & 110\end{array}$$
Set up the null hypothesis for the claim that the intervention protocol is effective in increasing scores.

A) H₀: The probability distribution of test scores before and after the intervention protocol is identical.
B) H₀: The probability distribution of test scores before the protocol is shifted to the left of the probability distribution of the test scores after the protocol.
C) H₀: The probability distribution of test scores before the protocol is shifted to the right of the probability distribution of the test scores after the protocol.
D) H₀: The probability distribution of test scores before the protocol is shifted to the left or right of the probability distribution of the test scores after the protocol.