Context: In a group of American curl cats, some individuals have curled ears and others have straight ears. In this group, the gene for the ear type trait has two alleles. The allele for straight ears (e) is recessive to the allele for curled ears (E).
This Punnett square shows a cross between two American curl cats.
What is the probability that an American curl cat produced by this cross will be heterozygous for the ear type gene?
A. 0/4
B. 3/4
C. 2/4
D. 4/4
E. 1/4
Answer with the option's letter from the given choices directly.

C