The population of Spain is approximately four times the population of Portugal.

Suppose that a random sample is taken of 1,500 Spaniards and 1,500 Portuguese.

Explain why you believe that the standard error of the sample mean is:

(a) four times larger for the Spanish poll;

(b) four times larger for the Portuguese poll;

(c) twice as large for the Spanish poll;

(d) twice as large for the Portuguese poll; or

(e) the same for both polls.