Answer:
By definition, tissues are absent from unicellular organisms. Even among the simplest multicellular species, such as sponges, tissues are lacking or are poorly differentiated. But multicellular animals and plants that are more advanced have specialized tissues that can organize and regulate an organism’s response to its environment.
Solar energy.
This is because the solar energy arrives and is trapped as radiation and heat.
The greatest degree of genetic variation would be found in an offspring resulting from sexual reproduction.
<u>Explanation:</u>
Asexual reproduction produces very less variations. Asexual reproduction requires only one parent and thus the offspring would be very similar to the parent. The chance of variations in offspring is very less.
But the case of sexual reproduction is different. Sexual reproduction involved two parents and each parent contribute equal amount of genetic material to the progeny.
Some characters of the offspring will be like one or the other parent and some characters will be a combination of the characters of both parents
. Such a combination produces variant offspring.
Birds were a major widespread during this time period therefore the answer is the last option
