Option 1: 1973 - This option suggests that Sikkim was granted statehood in the year 1973. However, this is incorrect as the correct answer is option 3.

Option 2: 1974 - This option suggests that Sikkim was granted statehood in the year 1974. However, this is incorrect as the correct answer is option 3.

Option 3: 1975 - This option is the correct answer. It states that Sikkim was granted statehood in the year 1975.

Option 4: 1976 - This option suggests that Sikkim was granted statehood in the year 1976. However, this is incorrect as the correct answer is option 3.

Therefore, the correct answer is option 3, which states that Sikkim was granted statehood in the year 1975.