I'd say b, but I feel this could be somewhat open to interpretation.
Answer:
The center of each interval is the same. The widths of the intervals are larger using the t distribution than the z distribution with s. This is caused by the fact that the critical value for z, zα/2, is less than the critical value for t, tα/2,n-1.
Ones upon a time, in my math exem I could't solve a really hard task.
Luckelly I had a smart watch and before the exem I took some photo about the math formulas, what I should learn. I turned on my watch and I started to see what formula I needed, suddely my benchmate stand up, and unfortunatally the teacher cought me, the worst of all was that she said that I have to leave the exem, before I can finish it.
