the important thing here is to read the whole sentence, and not make decisions based on only what is underlined.
Lower-level management function most effectively when they have thorough training and unimpeded communication with workers, supervisors, and one another.
(A) management function most effectively when they have - SV-agreement error. management functions
(B) managers function most effectively when they have - hold to it
(C) management functions most effectively when they have - pronoun they refers to singular noun management. incorrect.
(D) managers function most effectively when they have received - although it looks good, present perfect here is not needed. the sentence talks about general fact.
(E) management functions most effectively when it has = looks good..but wait..in the non-underlined portion, we have communication with... an one another. on this account, this answer choice is incorrect.