The answer is B.
If you put one plant in wet soil, and one plant in dry soil, you can prove or disprove your hypothesis as the plants grow.
MRNA has a complex secondary structure; 3D. While tRNA is more like an X figure.
Light is to find the distance between planets called light years.
For him they were just discrete physical units of inheritance. Johanson coined the term "gene" and people started calling them genes. Today for us these factors are parts of DNA, the base sequences that carry the biological information to determine a trait. Mendel factors are alleles of genes.