Final answer:
The correct statement is only statement 2, which says the maximum observed frequency of recombination for genes far apart is 50%. The other statements regarding gene proximity and crossovers, and traits studied by Mendel are incorrect.
Step-by-step explanation:
The question pertains to the principles of genetic linkage and recombination. Statement 1 is false because the closer two genes are on a chromosome, the lower the probability that a crossover will occur between them, not higher. Statement 2 is true; the observed frequency of recombination for genes that are far apart has a maximum value of 50%. This is because the genes act as if they are on different chromosomes and can independently assort. Statement 3 is false; while Mendel studied several traits, seed color and flower color are not necessarily linked on the same chromosome. Thus, the correct answer is that only statement 2 is true, making option 4 ('Only B and C are correct') incorrect because statement 3 is not correct, and therefore option 5 ('A, B, and C are correct') is also incorrect.