Explanation:

All statements are correct.

• The Agreement on Agriculture is aimed to remove trade barriers and to promote transparent market access and integration of global markets.

Three pillars of Agreement on Agriculture:

• Domestic Support: It calls for reduction in domestic subsidies that distorts free trade and fair price.
• Under this provision, the Aggregate Measurement of Support (AMS) is to be reduced by 20% over a period of 6 years by developed countries and 13% over a period of 10 years by developing countries.

Under this, Subsidies are categorized into:
Green Box

• Subsidies that do not distort trade, or at most cause minimal distortion.
• They are government-funded and must not involve price support.
• They also include environmental protection and regional development programmes. 
• “Green box” subsidies are therefore allowed without limits, provided they comply with the policy-specific criteria.

Amber Box

• All domestic support measures considered to distort production and trade (with some exceptions) fall into the amber box as all domestic supports except those in the blue and green boxes.
• These include measures to support prices, or subsidies directly related to production quantities. 

Blue Box

• This is the “amber box with conditions”. Such conditions are designed to reduce distortion.
• Any support that would normally be in the amber box is placed in the blue box if the support also requires farmers to limit production.
• At present, there are no limits on spending on blue box subsidies.

Hence option 4th is correct.