Best Answer Explained in Below-:

The term "Diamond Jubilee" typically refers to the celebration of a significant event's 60th anniversary, usually associated with a monarchy or notable historical occasion. However, in the context of the question asking about the 6th anniversary, it appears that there has been a mix-up in the options provided, as the correct term for a 6th anniversary is "Iron" or "Sugar Jubilee" in some contexts.

To clarify further, anniversaries often have specific names associated with certain milestones:
- A "Silver Jubilee" (25 years) marks a quarter-century anniversary,
- A "Golden Jubilee" (50 years) signifies half a century,
- A "Diamond Jubilee" celebrates 60 years,
- A "Platinum Jubilee" refers to 70 years.

However, since the question specifically asks for the name of the 6th anniversary, none of the options provided accurately match mainstream terminology. Therefore, option D ("none") could arguably be a more fitting answer, as none of the provided terms correctly represent the 6th anniversary. Thus, while "Diamond Jubilee" is notable for its significance, it does not correspond to the event of interest in this specific context.