what is a 'conjugative plural'?

[Miron]

English Language Tests, Intermediate level

ESL/EFL Test #219 "Confusing Words test (2)", question 5

Sometimes, there is a lot of animosity between friends. This will certainly cause those ......... relationships to fail.

(a) personnel
(b) personification
(c) personal
(d) personality

English Language Tests, Intermediate level

ESL/EFL Test #219 "Confusing Words test (2)", answer 5

Sometimes, there is a lot of animosity between friends. This will certainly cause those personal relationships to fail.

Correct answer: (c) personal
_________________________

can personnel be treated as a conjugative plural?

Miron

[Mister Micawber]

.
And what is a 'conjugative plural'?
.
_________________
Native English teacher at Mister Micawber's