Consider the following statements and choose the correct answer:
1. Petkus winter rye may be vernalized in the seed stage
2. Petkus winter rye has an obligate requirement for vernalization
3. Under continuous light, unvernalized Petkus winter rye will "head" in 15 weeks
4. Petkus winter rye differs from henbane in that the vernalization stimulus, once received, is not transmitted across a graft union

A. 1, 2 and 3 are true

B. 2 and 3 are true

C. 2, 3 and 4 are true

D. 1, 3 and 4 are true

Answer: Option D