Final answer:
In the phrase 'all the guests', the proper simple future tense verb form is 'will wear' to show that wearing white is an action that will happen at the upcoming wedding.
Step-by-step explanation:
The sentence 'They are getting married on Saturday. All the guests will wear white colour.' uses the simple future tense. The simple future tense of 'wear' is 'will wear', indicating that the action (wearing white) is expected to take place in the future, specifically on the day of the wedding.
In various cultures, white is traditionally associated with weddings, symbolizing purity and new beginnings. While traditions continue to influence wedding attire decisions, the expectation for guests to wear white is a unique request that diverges from the common practice of the couple dressing in particular wedding attire.