A researcher is interested in whether people's stress levels vary depending on the time of year. the researcher recruits five participants for their study. they ask the participants in mid-July on a scale from 1 to 20. how stressed they felt on average(where a higher score means greater stress) Then, in mid-January, they asked the same five participants again to report how stressed they felt on average. their average stress levels in July were 1 and January they were 15.

On a separate piece of paper, construct a sampling distribution of mean difference scores representing if the null hypothesis is true. What is the sampling distribution's mean?

A)u_MD=-4.00

B)u_MD=0.00

C)u_MD=15.00

D0u_MD=11.00