E. None of these make an inflation target less credible
Explanation:
Inflation target as the name implies is the monetary policy whereby the central bank of a particular country sets a specific inflation rate as its goal with the aim to create the impression that prices of goods and services will continue to increase. This will propel the economy to grow by making the citizens to buy things now before they cost more in the future.
Since the inflation target is set by central bank, it is usually credible and hardly have any reason that would create the impression ofbeing less credible.
In science, a broad idea that has been repeatedly tested and verified, giving scientists great confidence that it represents reality, is called a theory. A theory is a repeatedly test and proven idea by experimentation, theories are facts like the law of gravity, until disproved.