20.9Melody note alone gives candidates

We learned this in Module 7.

In C major:

Melody C

possible: C, Am, F

D

Dm, G, B°

E

C, Em, Am

F

Dm, F, B°

G

C, Em, G

A

Dm, F, Am

B

Em, G, B°

Now combine this with bass and function.

That often leaves one obvious answer.