Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: a circle graph can be used to display percents. 
Sentence2: pie charts are circle graphs.
circle

Sentence1: the ovaries are used in reproduction. 
Sentence2: Egg released by the ovary.
ovaries

Sentence1: Because of the asymmetry of the sugar, a polynucleotide chain has inherent polarity. 
Sentence2: Many nucleotides bind together to form a chain that because of asymmetry of sugar has inherent polarity.

Because