Consider the following code that will assign a letter grade of $\text{'}$A$\text{'},\text{'}$B$\text{'},\text{'}$C$\text{'},\text{'}$D$\text{'},$ or $\text{'}$F$\text{'}$ depending on a student's test score.

if $($score $>=90)$ grade $=\text{'}$A$\text{'}$;

if $($score $>=80)$ grade $=\text{'}$B$\text{'}$;

if $($score $>=70)$ grade $=\text{'}$C$\text{'}$;

if $($score $>=60)$ grade $=\text{'}$D$\text{'}$;

else grade $=\text{'}$F$\text{'}$;

A$.$ This code will work correctly in all cases

B$.$ This code will work correctly only if grade $>=60$

C$.$ This code will work correctly only if grade $<60$

D$.$ This code will work correctly only if grade $<70$

E$.$ This code will not work correctly under any circumstances

You must explain your answer$($s$).$ Simply stating the answer$($s$)$ will result in $0$ points awarded