Question

Mis maestros __________ (necesitar) papel.

Answer 1

Mis maestros necesitan papel.

Answer 2

Mis maestros necesitan papel.
Again, similar to the previous question, since this is third person plural (they), you would use the verb form ending in -n, such as necesitan, since that is the plural form.
Necesitamos is used for we.
Necesito is used for I.
Necesitais is used for you, plural.