A partial answer is when the team’s votes are divided equally between two different answers. In such cases, the team is granted 5 points out of the 10 available. Note that you have to pick the correct answer out of 3 options.
Imagine now you’re in a team of 6 players: if each potential answer has 2 votes, this won’t count as a partial answer but will rather be considered as wrong. To be counted as a partial answer, the votes really need to be split between two answers in a 50-50 manner.