Step 1: Read the question.
We must find the method in which learners are most passive.
Step 2: Meaning of passive learning.
A learner is passive when they mainly sit and listen and receive information, without doing, discussing, or solving anything.
Step 3: Look at active methods.
In the discussion method students talk and share. In demonstration they watch and respond. In the project method they explore and build. All these keep students active.
Step 4: Look at the lecture method.
In the lecture method the teacher speaks most of the time and students mostly listen and take notes. There is little doing.
Step 5: Compare and decide.
Since the lecture method involves the least student doing, it makes learners the most passive.
Step 6: Final answer.
Learners' participation is most passive in the lecture method.
\[ \boxed{\text{Lecture method.}} \]