TOPIC: PMI Mock Exam Question...why this answer?

I'm writing the PMI Free mock exam, and I'm not understanding the answer to this question, would anyone know the rationale?

Question: To effectively lead a project team, a project manager must help team members grow and keep them motivated throughout the project. What should a project manager do to accomplish this?"
a) Delegate project tasks that challenge the team
b) Be assertive and stand up for the team's beliefs
c) Reward the team for each task that is successfully completed
d) Conduct daily feedback sessions to understand the teams concerns.

Upon reading the question, my first though would be "Develop Team" process and I would think the answer is a) with a possibility of c).
But the answer was b). The explanation was: "The Primary goal of a PM in relation to the team project team is to ensure that the team has the time and resources to do their job and to remove any barriers they may encounter. By standing up for the team's beliefs the project manager is demonstrating their support for the team"

The question doesn't have any hints of barriers that need to be removed, it talks about growth and motivation, I'm not understanding the PMI answer.

I swear I could have written this post. I had the exact same thought process when I took that exam yesterday. It seemed like the PMI exam had a couple of questions in which the scenario wasn't fully in line and/or explained with the reasoning that was provided.

Concentrate the hints Help team member to grow which indicstion of servant leadership style

JDK et al.:

Here is my reasoning for "B"

1. "Delegate project tasks" is not a leadership function; it is a management function, so "A" is eliminated.
2. "Conduct daily feedback sessions" is more management and information gathering, so "D" is eliminated.

That leaves only B and C as possible answers. Of those "B" (Assertiveness and standing for team beliefs) is the best answer because it demonstrates leadership. "Rewards" is possible as it is a leadership style, but not the best answer.

Harry

I managed to select B through elimination and this is how (Though initially was confused between A and B )
A: Delegating challenging project task may not motivate the team . remember challenging tasks are difficult to accomplish too. This option was 50-50
B: The only remaining option , better than A
C: reward the team for each task . This would have been the right option had the team members been rewarded for the challenging tasks, not each tasks. Will you feel motivated if u get rewarded for each task completed. After a while, getting the reward would become a routine.
D:Conduct daily feedback sessions. First the word daily; doing daily feedback session may not be productive (weekly/bi-weekly once or so). Besides, what you do after getting the feedback is more important for team motivation/growth, which is not mentioned in this option