Which of the following statements are true?

a. The original sample can contain serial numbers that are not in the resample.
b. Because the sample size is small, the histogram of the resample might look very different from the histogram of the original sample.
c. The resample can contain serial numbers that are not in the original sample.
d. The original sample has exactly one copy of each serial number for every German plane.
e. The resample has either zero, one, or more than one copy of each serial number.
f. The resample has exactly the same sample size as the original sample.