how do firms typically reduce costs through horizontal integration?

Response $1$ of $3$: By reducing quality through larger production quantitiesBy reducing quality through larger production quantitiesResponse $2$ of $3$: By gaining access to cheaper suppliers that the other company already has access to By gaining access to cheaper suppliers that the other company already has access to Response $3$ of $3$: By gaining economies of scale through increased purchasing power from the larger sizeBy gaining economies of scale through increased purchasing power from the larger size