Read the following text and answer:

There is an oil refinery which refines crude petroleum and sells it in the market. The output of the refinery is the amount of oil it refines. We can estimate the value added of the refinery by deducting the value of intermediate good used by the refinery from the value of its output. The value added of the refinery will be counted as part of the GDP of the economy. But in carrying out the production the refinery may also be polluting the nearby river. This may cause harm to the people who use the water of the river. Hence their well being will fall. Pollution may also kill fish or other organisms of the river on which fish survive.

1. If the GDP of the country is rising, the welfare will always rise.
2. Externalities refer to the benefits a firm or an individual cause to another for which they are not paid.
3. Non-monetary exchanges are excluded in the estimation of GDP.
4. Adding the value of final goods once leads to problem of double counting.

B and C only

Gross Domestic Product does not take into account changes in a nation's income distribution. Consequently, a gain in GDP may not always translate into an improvement in people's welfare.

Externalities refer to the benefits (or harms) a firm or an individual causes to another for which they are not paid (or penalised).

Non-Monetary Exchanges are activities that cannot be valued in terms of money and are therefore excluded from the calculation of GDP. These actions nevertheless have an impact on the economy. Therefore, their elimination may result in a lower estimate of GDP. 

Adding the value of intermediate goods leads to the problem of double counting.