What is a similarity between dna and rna a) both are polymers of nucleotides b) both are composed of antiparallel strands c) both contain adenine, cytosine and thymine d) both contain ribose sugar

Let's use process of elimination to answer this question!

D is wrong, and we know this because of the names of DNA and RNA. The D in DNA stands for deoxyribose, and the R in RNA stands for ribose. These are the types of sugars in each nucleic acid. Therefore, they don't both contain a ribose sugar.

C is wrong, and this is because RNA does not contain thymine, but uracil instead.

B is wrong, and we know this because we know that RNA is composed of only one strand, and therefore it is not composed of multiple stands (plural).

Therefore, A must be right. We can confirm this, because we know that polymers are large molecules consisting of repeated subunits. DNA and RNA are both polymers consisting of nucleotides.