单选题 According to the explanation of the scientific rule of experiment in the passage, "hard-and-fast" means experiment procedures ______.

A、 are difficult and quick to follow
B、 must be carried out in a strict and quick way
C、 must be followed strictly to avoid false and loose results
D、 hard and unreasonable for scientists to observe

【正确答案】 C

【答案解析】文中对其的解释“a problem set up and solved by one scientist must be tested by other scientists，under identical conditions and reaching identical results”与C“必须严格遵循，以免出现假的和不严谨(不确切)的结果”相符。