Normal probability curve should be

Positively skewed
Negatively skewed
Leptokurtic skewed
Zero skewed

The correct answer is A. Positively skewed.

A normal probability curve is a bell-shaped curve that is symmetrical around the mean. The mean, median, and mode are all equal in a normal distribution. The curve is also asymptotic to the x-axis, which means that it approaches but never touches the x-axis.

A positively skewed distribution is one in which the mean is greater than the median. This means that the majority of the data points are clustered towards the lower end of the distribution, with a few data points that are much higher than the rest.

A negatively skewed distribution is one in which the mean is less than the median. This means that the majority of the data points are clustered towards the higher end of the distribution, with a few data points that are much lower than the rest.

A leptokurtic distribution is one that is more peaked than a normal distribution. This means that the data points are more tightly clustered around the mean.

A platykurtic distribution is one that is less peaked than a normal distribution. This means that the data points are more spread out around the mean.

A zero skewed distribution is one that is symmetrical around the mean. This means that the mean, median, and mode are all equal.