Under Article XII, Section 3, lands of the public domain are classified into agricultural, forest or timber, mineral lands, and national parks. Which of these may be alienated?

The correct answer is B. Agricultural lands only

Section 3 states that agricultural lands of the public domain may be further classified by law according to the uses to which they may be devoted, and that "alienable lands of the public domain shall be limited to agricultural lands." The other classes remain with the State.