RNA is thought to have proceeded proteins and DNA, why?

A. more types of RNA than DNA
B. single stranded RNA is less complex than DNA
Not sure if either are correct?

I sincerely hope your teacher meant "Preceeded".

A is sort of true, depending on what one considers a type.
B is true, but that is hardly the reason for most folks looking at the evolution of RNA to DNA systems. If you are interested, here it is ..http://www.ncbi.nlm.nih.gov/books/NBK26876/

I would go with B, then maybe argue with your teacher over A. Neither is a good answer.

To determine why RNA is believed to have preceded proteins and DNA, let's analyze the options.

Option A suggests that RNA has more types than DNA. However, this statement is incorrect. DNA actually has more different types than RNA, as DNA is composed of four different nucleotide bases (adenine, thymine, cytosine, and guanine), while RNA is composed of only three (adenine, uracil, cytosine, and guanine). Therefore, option A is not the correct answer.

Option B suggests that single-stranded RNA is less complex than DNA. This is indeed true. RNA is typically single-stranded, whereas DNA is double-stranded. Single-stranded RNA is simpler in structure compared to the double helix structure of DNA.

Based on this information, we can conclude that option B is the correct answer. RNA is believed to have preceded proteins and DNA because single-stranded RNA is less complex than double-stranded DNA. This simplicity may have made it easier for RNA to emerge as the primary genetic material before the formation of more complex DNA.