Which of the following statements concerning the standard normal curve is/are true (if any)?

a) the area under the standard normal curve to the left of -3 is zero.

b) the area under the standard normal curve between any two z-scores is greater than zero.

c) the area under the standard normal curve between two z-scores will be negative if both z-scores are negative.

d) the area under the standard normal curve to the left of any z-score is less than 1.

a. a, b
b. b, d
c. a, c
d. a