The provided answer, option 5, is incorrect as there are only four options given in the question.

To determine the correct answer to this question, we need to assess each country`s proximity to the Indonesian Ocean and the extent of damage caused by the tsunami.

Option 1: Indonesia is the epicenter of the tsunami and was the most severely impacted country. The tsunami caused significant damage and resulted in the loss of thousands of lives.

Option 2: Malaysia is located further away from the epicenter compared to Indonesia. Although it experienced some effects of the tsunami, the impact was relatively less severe compared to Indonesia.

Option 3: Sri Lanka is not directly located in the Indonesian Ocean but lies in the Indian Ocean. It was also affected by the tsunami, and the damage was substantial with numerous casualties reported.

Option 4: India, like Sri Lanka, is located in the Indian Ocean but not directly in the path of the tsunami. However, it still experienced some impacts, particularly in the southern coastal regions.

Based on this assessment, option 2 - Malaysia - was the least affected by the tsunami among the given options.