Why must certain flowers be treated separately from others during arrangement?

Certain flowers must be treated separately from others during arrangement primarily because they produce ethylene gas, which can negatively impact the longevity of nearby flowers. Ethylene is a natural plant hormone emitted by some flowers and fruits, and it can accelerate the aging process in other flowers, causing them to wilt or decay more quickly.

By isolating ethylene-producing flowers, florists can prolong the life and beauty of the entire arrangement. This practice ensures that flowers sensitive to ethylene do not suffer from its effects, allowing arrangements to remain fresh and vibrant for a longer period.

The other choices, while relevant to some degree in floral care, do not specifically address the critical issue of ethylene production and its consequences in mixed arrangements. Understanding the ethylene sensitivity among different floral varieties is essential for maintaining optimal freshness in any floral arrangement.