A Team of Researchers Designed a 20-Question Likert Scale to Measure

A team of researchers designed a 20-question Likert scale to measure attitudes on immigration.They administered the survey to 100 participants.Which of the following techniques could they use to assess the reliability of their scale?

A) Administer the same survey to 100 different participants six months later, and compare the first results with the second results
B) Administer the same survey to the same 100 participants six months later, and compare the first results with the second results
C) Randomly divide the scale into two groups of ten, calculate a score or each respondent on each group of ten, and compute a correlation between the two scores
D) Both B and C