Final answer:
The total product curve generally increases at an increasing rate, then at a decreasing rate, resembling an s-shape, while a. the marginal product curve often has a bell-shaped form, starting high, decreasing.
Step-by-step explanation:
The shape you would generally expect for a total product curve is one that increases at an increasing rate, then at a decreasing rate, and eventually may decline. This implies that initially, as input increases, total output increases at a higher rate due to increasing returns to scale or more efficient utilization of fixed resources. However, after reaching a point of maximum efficiency, the curve increases at a decreasing rate due to diminishing marginal returns, and finally, might even go down if the input becomes too much to be handled efficiently. Consequently, the total product curve is not linear; it is typically s-shaped.
In contrast, the marginal product curve starts high when the first units of input are used, then decreases, often following a smooth curve that first slopes downward sharply and then more gently, often taking on a bell-shaped form before it eventually turns negative when the total product starts to decrease. Initially, each additional unit of input yields more output, but after the optimal level of input is exceeded, each additional unit of input produces less additional output, and thus the marginal product falls.
Therefore, the correct answer is: a. Total product curve is linear, marginal product curve is bell-shaped, although this description might be overly simplified as the total product curve is typically s-shaped rather than strictly linear.