Which of the following statements best differentiates a null hypothesis from an alternative hypothesis in scientific research?
a. The null hypothesis proposes a relationship between variables, while the alternative hypothesis suggests no relationship.
b. The null hypothesis assumes no effect or no difference, while the alternative hypothesis posits an effect or difference.
c. The null hypothesis is supported by experimental evidence, while the alternative hypothesis is rejected if evidence contradicts it.
d. The null hypothesis is a prediction made before conducting experiments, while the alternative hypothesis is a prediction made after analyzing experimental results.