All of the following are possible causes for a mood disorder except factors.
a.
biological
b.
psychological
c.
environmental
d.
religious

D.) Religious

A and B are common mood disorder causes and environmental can be very true because some people just might not like the environment they are in.

The correct answer for the blank is -

D. Religious.

Explanation:

Mood disorder can be described as psychological disorder or a mental illness /state of a person that is mainly characterized by the increase or decrease in the mood of person with respect to the circumstances around him.

In other words, the emotional state of a person gets distorted and person becomes unable to work properly. There can be various reasons, which may include biological factors, phychological or environmental factors. It has no religious cause, as religious factors does not alter the emotional state of any person.

Example - depression or bipolar disorder.

Thus, option D) is the right answer.

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation:

oxygen +1 most likely