Answer:
E. ALL STATEMENTS ARE TRUE
Step-by-step explanation:
PPF is representation of two goods that can be produced by an economy, given resources & technology. It is downward sloping because of negative relationship between two goods given same resources & technology.
Opportunity cost is the cost if next best alternative forgone while making a choice. In this case it is amount of Good A sacrifised to gain Good B.
Choice GoodA GoodB Opportunity Cost [ ∆GoodA/∆GoodB ]
1 100 0 _
2 90 20 -10:20 (90-100) : (20-0)
3 70 40 -20:20 (70-90):(40-20)
4 40 60 -30:20 (40-70): "
5 0 80 -40:20 (0-40): "
So : Options A,C,D - all are correct. From Choice 1 to 2, 20 good B have been gained by sacrifising 10 good A. From Choice 2 to 3, 20 good B have been gained by sacrifising 20 good A. From Choice 3 to 4, 20 good B have been gained by sacrifising 30 good A.
Option B is also correct: As the Opportunity cost of gaining same amount of good B (in terms of sacrifised good A) is increasing each time successively over its preceding good A sacrifise. [10 < 20 < 30 < 40]. This makes PPF concave also.