The Correct Answer is Option C: BDFH

To determine the series in which the number of letters skipped between adjacent letters is the same, we need to analyze each option and look for patterns or rules.

Option A: AGJI
- The letters in this series are A, G, J, and I.
- There is a gap of 6 letters between A and G.
- There is a gap of 3 letters between G and J.
- There is a gap of 2 letters between J and I.
- Therefore, the number of letters skipped between adjacent letters is not the same, so option A is incorrect.

Option B: AFKL
- The letters in this series are A, F, K, and L.
- There is a gap of 5 letters between A and F.
- There is a gap of 5 letters between F and K.
- There is a gap of 1 letter between K and L.
- Therefore, the number of letters skipped between adjacent letters is not the same, so option B is incorrect.

Option C: BDFH
- The letters in this series are B, D, F, and H.
- There is a gap of 2 letters between B and D.
- There is a gap of 2 letters between D and F.
- There is a gap of 2 letters between F and H.
- Therefore, the number of letters skipped between adjacent letters is the same (2), so option C is the correct answer.

Option D: JNPR
- The letters in this series are J, N, P, and R.
- There is a gap of 4 letters between J and N.
- There is a gap of 2 letters between N and P.
- There is a gap of 2 letters between P and R.
- Therefore, the number of letters skipped between adjacent letters is not the same, so option D is incorrect.

Conclusion
Based on the analysis, we can conclude that the series in which the number of letters skipped between adjacent letters is the same is option C: BDFH.