College Students Tested to See If How Well You Know

College students tested to see if how well you know a person affects your ability to detect a lie from that person. To do this, they came up with 10 statements about a person in their group. Five of these statements were true and five were False. The group tried to make up statements that no-body (not even close friends) would know if they were true or False. The students then presented these statements to people that fit in three groups: close friends, acquaintances, and complete strangers and counted how many statements each person correctly identified as true or False. A summary of the results are as follows.
-If the Mean Group Diff statistic had been smaller than the observed Mean Group Diff statistic calculated in question 12, how would the strength of evidence change?

A) The strength of evidence against the null would increase.
B) The strength of evidence against the null would decrease.
C) The strength of evidence against the null would stay the same.