Answer: A six month T-bill rate of 1.9 %
Step-by-step explanation:
As all the instruments are similar in terms of maturity period and return rate, the most desirable will be in terms of the one with the lowest risk.
The United States T-bill is one of the safest instruments in the world as it is backed by the full faith of the United States Government which has technically never defaulted on debt. This is therefore the lowest instrument listed and is therefore the most desirable.