a$.$ char letters$[5]=\{\text{'}$a$\text{'},\text{'}$b$\text{'},\text{'}$c$\text{'},\text{'}$d$\text{'},\text{'}$e$\text{'}\}$;

b$.$ char letters$[5]=\{"$a$","$b$","$c$","$d$","$e$"\}$;

c$.$ char letters$[5]=\{\text{'}$a$\text{'}$; $\text{'}$b$\text{'}$; $\text{'}$c$\text{'}$; $\text{'}$d$\text{'}$; $\text{'}$e$\text{'}\}$;

d$.$ char letters$[5]=\{"$a$"$; $"$b$"$; $"$c$"$; $"$d$"$; $"$e$"\}$;