A cross did between a homozygous recessive and a heterozygous plant is called as 

1. A test cross is a cross between homozygous plants with recessive characteristics and heterozygous plants. 
2. A test cross is a useful technique for determining the organism's genotype. 
3. Gregor Mendel invented the test cross with the intention of determining if a plant's genotype was homozygous dominant (AA) or heterozygous (Aa). 
4. Identification is impossible since both genotypes yield the dominant phenotypic traits. The test cross is an easy way to identify the real breeds. 
5. A test cross is a tool for investigating an organism's genetic makeup. 
6. The test cross was initially employed as an investigative mating test to identify the genotype's allele composition.

Hence, option C is the correct answer.