Final answer:
The probability of selecting a donut that is not Jennifer's is 19 out of 24, since there are 19 donuts that are not marked as Jennifer's in a box of 24.
Step-by-step explanation:
When Elizabeth selects a donut, there are 24 in total and 5 are Jennifer's. To find the probability of selecting a donut that is not Jennifer's, we subtract the number of Jennifer's donuts from the total number of donuts. This gives us 24 - 5 = 19 donuts that are not Jennifer's. Hence, the probability of picking a donut that is not Jennifer's is the number of donuts that are not hers divided by the total number of donuts.
Therefore, the calculation is 19/24. Answer choice 3) 19/24 is the correct option.