A sociologist recorded the number of contacts entered in a cell phone and the number of texts sent in a week for 20 cell phone users. The resulting data were used to conduct a hypothesis test to investigate whether there is a linear relationship between the number of contacts and the number of texts sent. What are the correct hypotheses for the test?

a. H0:β1=0 Ha:β1≠0

b. H0:β1=0 Ha:β1>0

c. H0:β1=0 Ha:β1<0

d. H0:β1≠0 Ha:β1=0

e. H0:b1=0 Ha:b1≠0