Question $1$

The target population is all stocks in the S&P $500$ index. Is each of the following a parameter or a statistic?

A$.$ The average price$/$earnings ratio for all $500$ stocks in the S&P index.

B$.$ The proportion of all stocks in the S&P $500$ index that had negative earnings last year.

C$.$ The proportion of energy$-$related stocks in a random sample of $50$ stocks.

D$.$ The average rate of return for $20$ stocks recommended by a broker.