You are trying to determine if schizophrenics have altered levels of the hormone oxytocin. You take cerebral spinal fluid samples from 20 schizophrenic patients and 20 age and sex matched normal individuals. The levels of oxytocin are measured and compared. Based on this study, which statistical test should be used? Group of answer choices

1 tail paired t test

2 tail paired t test

1 tailed 2 sample t test

2 tailed 2 sample t test