Sperm height is not an essential feature of sperms that determine the fertility of a male. The correct answer is option 'C'. Let's discuss each option to understand why.

a) Sperm count:
Sperm count refers to the number of sperm cells present in a given sample. It is an important factor in determining male fertility because a higher sperm count increases the chances of successful fertilization. Low sperm count, also known as oligospermia, can reduce the probability of conception. Therefore, sperm count is a crucial feature for male fertility.

b) Sperm motility:
Sperm motility refers to the ability of sperm cells to swim and move effectively. It is an essential factor in fertility because sperm cells need to move through the female reproductive tract to reach the egg for fertilization. If the sperm cells do not have proper motility, they may not be able to navigate through the female reproductive system and fertilize an egg. Therefore, sperm motility is a critical feature for male fertility.

c) Sperm height:
Sperm height is not a recognized factor in determining male fertility. The concept of sperm height is not commonly used or recognized in scientific literature or medical practice. It is likely an incorrect or misleading term. As a result, sperm height does not play a role in determining male fertility.

d) Sperm production rate:
Sperm production rate refers to the rate at which sperm cells are produced by the male reproductive system. It is an essential factor in fertility because a sufficient production of healthy sperm cells is necessary for successful fertilization. If the production rate is low, it can lead to a reduced number of sperm cells available for fertilization. Therefore, sperm production rate is a crucial feature for male fertility.

In conclusion, among the options given, sperm height is not an essential feature of sperms that determine the fertility of a male. Sperm count, sperm motility, and sperm production rate are all important factors that contribute to male fertility.