How does recursive design differ from top$-$down design?

a$.$

Recursive design focuses on optimizing code efficiency, while top$-$down design focuses on problem decomposition.

b$.$

Recursive design involves calling a function within itself, while top$-$down design does not.

c$.$

Recursive design starts with low$-$level implementation details, while top$-$down design starts with a high$-$level overview.

d$.$

Recursive design is only applicable to certain types of problems, while top$-$down design is more universal.