Question

All the committee members have arrived at on decision correct it using articles ​

Answer 1

All the committee members have arrived at a decision.

Or  

All the committee members have arrived on a decision.

Explanation:

• There are two articles in the English grammar that are "the and a/an".

• "the" is considered as a definite article and "a/an" is considered as an indefinite article.

• Article "the" is used to refer to the specific nouns. It can be used for singular as well as plural nouns.

• "a/an" article is used for the unspecific nouns. It is used for singular nouns.

Answer 2

Answer:

All the committee members have arrived at a decision.