An import threshold for mercury in crayfish is 9 parts per billion (ppb). A study obtained a random sample of 120 crayfish from a large lake. Of these, 24 have levels of mercury that exceeded 9 ppb. Past research had shown that 25% of the crayfish had levels that exceed 9 ppb. Based on new water standards for manufacturers in the region, they wanted to see if there was a change in contamination in crayfish. What are the appropriate null and alternative hypotheses? (NE means not equal.)
A. Ho: p = .25 and Ha: p > .25
B. Ho: p = .25 and Ha: p NE .25
C. Ho: p = .25 and Ha: p > .20
D. Ho: p = .25 and Ha: p < .25