Which of the following signals the start of a new expansion?

In a perfectly competitive industry, i. entry by new firms shifts the market supply curve rightward. ii. exit by existing firms shifts the market supply curve leftward. iii. at all times existing firms make only zero economic profit

A) ii and iii B) ii only C) i and iii D) i and ii E) i, ii, and iii

If a tax of $1 a can is imposed on the buyers of sugary drinks, the demand for sugary drinks ______ and the price that buyers pay ______

A. doesn't change; doesn't change B. doesn't change; rises by $1 a can C. decreases; rises by more than $1 a can D. decreases; rises by less than $1 a can