A low rate of interest

brings down wages
increases wages
itself insufficient to raise investment
is always due to central bank's order to the entire money market

The correct answer is C. itself insufficient to raise investment.

A low interest rate can make it cheaper to borrow money, which can encourage businesses to invest in new projects. However, there are other factors that also affect investment, such as the availability of credit, the level of economic activity, and the expectations of businesses about future profits. Therefore, a low interest rate is not always sufficient to raise investment.

Option A is incorrect because a low interest rate does not necessarily lead to lower wages. In fact, a low interest rate can lead to higher wages if it leads to increased economic activity and higher demand for labor.

Option B is incorrect because a low interest rate does not necessarily lead to higher wages. In fact, a low interest rate can lead to lower wages if it leads to increased unemployment and lower demand for labor.

Option D is incorrect because a low interest rate is not always due to the central bank’s order to the entire money market. The central bank can influence interest rates, but it does not have complete control over them. Interest rates are also affected by market forces, such as the supply and demand for money.