Directions: In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.

Oil is almost certainly one of the ocean's greatest resources. 33% of the world's oil comes from seaward fields in seas. Oils are liquids that easily burn and do not (1)______ in water. Most of the time, they are made of chains of carbon and hydrogen atoms. There are three (2)______ types of oils: mineral, essential and fixed oils. From plants, essential oils are thin, scented oils. Because they frequently have an odour, essential oils are (3)______ in perfumery and food flavouring. Aromatic extraction processes like cold pressing, distillation and extraction are typically used to prepare essential oils. Fatty acids are used by animals and plants to make fixed oils. They are especially non-volatile oils that are found in the seeds of cotton, corn, flax, sunflowers, peanuts, coconuts and olives, as well as in fatty animal tissues. Mineral oils are (4)_______ from petroleum which has been underground for millions of years from sea organism skeletons. Mineral oils are one of the petroleum by-products with the lowest prices. Mineral oils are colourless and transparent. They are made up of a (5)_____ of hydrocarbons.

Select the most appropriate option to fill in blank number 3.

The correct answer is utilised.

Explanation:

Let us analyze the context of blank number 3 in the sentence:

"Because they frequently have an odour, essential oils are (3)______ in perfumery and food flavouring."

The sentence explains the practical application of essential oils because of their characteristic scent (odour). We need a verb that fits naturally in the passive voice construction "are ______ in [an industry/field]".

Let us examine the meanings of the given options:

1. Operated: Means controlled or functioned (e.g., operating a machine or business). It is not appropriate for materials or substances like oils.

2. Employed: Primarily used for giving work/jobs to people, or sometimes using a specific method/technique. While it can mean "used", it is less standard when talking about raw materials in industrial products compared to "utilised".

3. Applied: Means put on a surface or put into practical use, but usually requires prepositions like "to" (e.g., applied to the skin). It does not fit smoothly into "applied in perfumery and food flavouring" as a primary choice for resource usage.

4. Utilised: Means put to practical, effective, or profitable use. In scientific and informational passages, raw materials and natural resources (like essential oils) are described as being utilised in various industries (such as perfumery and food flavouring).

Therefore, utilised is the most appropriate option to complete blank number 3.