The Punnett square below represents a cross that produced two plants with orange flowers. If the orange color of the flowers is a result of incomplete dominance, what color were the flowers on the parent plants?

Incomplete Dominance: is a heterozygous condition from which an intermediate phenotype (physical expression) is shown because both alleles are partially expressed.

Orange (Rr) is most likely an intermediate of yellow (rr) and Red (RR). One example of this incomplete dominance domination pattern and colors in real life occurs in a type of peppers which come in only 3 colors (red, yellow, orange)