Here's a problem to solve: In pea plants, the allele for smooth peas is dominant (S). If a heterozygous smooth pea plant (Ss) is crossed with a homozygous smooth pea plant (SS), which are the possible genotypes the offspring could have?

Among the 4 following options, which is the correct answer?

- A: only SS
 
- B: only Ss
 
- C: Ss or SS
 
- D: ss or SS
 