Choose the option that best expresses the meaning of the English word "jubilant" by selecting its closest synonym.

Introduction / Context:
Vocabulary questions that ask for a synonym test a learner grasp of word meanings, shades of emotion and common usage. The word jubilant is often used in news reports and literature to describe people who are extremely happy and celebrating. To answer correctly, we must find the option that conveys a similar level and type of happiness.

Given Data / Assumptions:

The target word is jubilant.

The options are sombre, dejected, jocular, rejoicing and indifferent.

We need the nearest synonym, that is, the word that most closely matches jubilant in meaning.

Jubilant typically describes people who are very happy, often after a success or victory.

The question belongs to general English vocabulary, not technical usage.

Concept / Approach:
In English, jubilant means extremely joyful, triumphant or filled with great happiness, especially in response to a positive event. The key idea is intense joy and celebration. We must compare each option with this meaning. Words that express sadness or lack of emotion cannot be synonyms. The word rejoicing directly expresses joy and celebration and usually appears in contexts very similar to those in which jubilant is used.

Step-by-Step Solution:
Step 1: Recall the dictionary sense of jubilant as feeling or expressing great happiness and triumph. Step 2: Examine rejoicing. It comes from the verb rejoice, which means to feel or show great joy or delight. People who are rejoicing are clearly jubilant. Step 3: Examine jocular. Jocular refers to someone who is fond of joking or humorous. That person may be cheerful but the focus is on humour, not necessarily on triumphant joy. Step 4: Examine sombre and dejected. Both of these words relate to sadness or low spirits. Sombre means serious, dark or gloomy, and dejected means depressed or miserable. Step 5: Examine indifferent. Indifferent refers to lack of interest or concern, the opposite of an intense emotional response.

Verification / Alternative check:
Imagine a sentence from a news report: The crowd was jubilant after the team victory. Substitute rejoicing: The crowd was rejoicing after the team victory. The sentence remains natural and meaningful. Now try substituting jocular: The crowd was jocular after the team victory. This sounds strange and does not capture the atmosphere of triumphant celebration. Using sombre, dejected or indifferent would completely reverse the meaning, proving that they cannot be correct.

Why Other Options Are Wrong:
Sombre describes a serious or sad mood, often used for funerals or serious occasions, the opposite of jubilant. Dejected denotes sadness and disappointment, again the emotional opposite of great joy. Jocular involves joking, which may include light humour but not the strong sense of triumphant celebration that jubilant carries. Indifferent expresses lack of interest or concern and therefore does not convey any positive emotion at all.

Common Pitfalls:
Some learners confuse jocular with words for happiness because jokers often make people laugh. However, jubilant is stronger and linked to celebration or triumph, not simply to making jokes. Others may be misled by partial similarity in sound or by not reading all options carefully. Always focus on the intensity and type of emotion expressed by the word.

Final Answer:
The closest synonym of jubilant is rejoicing.