To find the correct answer, plug in all the words and see which one makes the most sense...
1. I went to baseball practice together today.
2. We went to baseball practice together today.
3. He went to baseball practice together today.
4. You went to baseball practice together today.
The word together in the sentence informs the reader that more than one person went to baseball practice. Some people went in a group. The only plural word is We.
Thus, the correct answer to this question is 2. We.
