Answer
(H) - A hypothesis.
Work Step by Step
''Sally thinks she may be allergic to shrimp'' is a hypothesis formed after the observation made in 1.8b, ''Yesterday, one hour after Sally ate a shrimp salad, she broke out in hives.''
After Sally ate a shrimp salad, she observed that she broke out in hives. Then, after wondering why that happened, Sally formed a hypothesis that she was allergic to shrimp.