Answer:
A. Skin color, a polygenetic trait, is also determined by environmental factors.
Explanation:
When you are a lifegaurd you are outside much more which means you are very likely to get a tan; Therefore changing the pigment of Pat's skin.
I hope this helps you :) Have a nice day!
Crossing over happens in Meiosis 1 only. In Prophase 1 a cells chromatin (chromatin = chromosomes that have not condensed yet) condense and pair up forming homologous chromosomes (paired = XX (2 chromosomes together)). When this happens segments/ alleles of the chromosomes pairing up swap over. This creates genetic diversity as each chromosome is different, it has parts from its pair. This leaves every chromosome unique and individual.
I hope this helps, sorry some of the vocab is rather technical. By the way I would suggest watching the
'Crash Course: Meiosis' on YouTube, this really helped me when I was learning this topic. :D