Question A3 (Version A) Bob runs a book-binding business, and the production of bound books requires two inputs: the binding machine and labour. The production function exhibits diminishing returns to labour. Which of the following statement is incorrect in the short run? (a) The production function is concave in the labour input. (b) Average total cost is increasing in output. (c) Short-run total cost is convex in output. (d) Variable cost is convex in output. (e) Marginal cost is increasing in output