A candidate for public office plans to visit each of the six cities J, K, L, M, N and O exactly once during her campaign. Her aides are setting up the candidate's schedule according to the following restrictions :
The candidate can visit M only after she has visited both L and N.
The candidate cannot visit N before J.
The second city visited by the candidate must be K.
Which of the following must be true of the candiate's campaign schedule ?

Options

A. She visit J before L.
B. she visit K before M.
C. she visit K before O.
D. She visit M before J

Explanation

To solve the problem, we need to establish the order of the candidate's visits to the cities J, K, L, M, N, and O while adhering to the given restrictions. Let's break it down step by step.

### Step 1: Identify the Fixed Position
The problem states that the second city visited by the candidate must be K. Therefore, we can establish the following initial structure:

1. _ (First city)
2. K (Second city)
3. _ (Third city)
4. _ (Fourth city)
5. _ (Fifth city)
6. _ (Sixth city)

### Step 2: Apply the Restrictions
Now, let's apply the restrictions one by one:

1. **M can only be visited after L and N**: This means that both L and N must be visited before M. We can represent this as:
- L, N → M (L and N must come before M)

2. **N cannot be visited before J**: This means J must come before N:
- J → N (J must come before N)

### Step 3: Combine the Restrictions
Now, we need to combine these restrictions to find a valid order:

- From the first restriction (L, N → M), we know that L and N must be before M.
- From the second restriction (J → N), we know that J must come before N.

This gives us a sequence where J must come before N, and both J and N must come before M. We can represent this as:
- J → N → M

### Step 4: Determine Possible Positions
Now we need to fit these into the structure we established in Step 1. Since K is fixed in the second position, we can place J, L, and N in the remaining positions.

Let’s consider the possible placements:
- J can be in position 1 (the only option left for J since K is in position 2).
- L can be in position 3, 4, or 5.
- N must be placed after J, which means N can be in position 3, 4, or 5 but must also be before M.

### Step 5: Final Arrangement
Given the above analysis, we can summarize the possible arrangement:
1. J (1st position)
2. K (2nd position)
3. L (3rd position)
4. N (4th position)
5. M (5th position)
6. O (6th position)

This arrangement satisfies all the conditions:
- J is before N.
- K is in the second position.
- M is after both L and N.

### Conclusion
From the analysis, we can conclude that the candidate must visit K before M, which is consistent with the restrictions provided.