The correct option is
A Single stranded DNA
RecA is a 38 kilodalton protein essential for the repair and maintenance of DNA. RecA's association with DNA major is based on its central role in homologous recombination. The RecA protein binds strongly and in long clusters to single stranded DNA to form a nucleoprotein filament. The protein has more than one DNA binding site, and thus can hold a single strand and double strand together. This feature makes it possible to catalyze a DNA synapsis reaction between a DNA double helix and a complementary region of single stranded DNA.
Therefore, the correct answer is option A.