Explanation:

- The sequence is presented as: gr__jk__rj__kg__jj__

- To complete the series, look for repeating patterns or sequences.

- The blank spaces need to be filled with the options provided.

Option 1: gjrrk

- Fills the blanks as: gr(jg)jk(rr)rj(jk)kg(jr)jj

- The letters do not create a consistent or logical sequence.

Option 2: jgjrk

- Fills the blanks as: gr(jg)jk(jr)rj(jk)kg(jr)jj

- This option shows a repeating sequence of "jr", making it logical and consistent.

Option 3: jgrrk

- Fills the blanks as: gr(jg)jk(rr)rj(kr)kg(jr)jj

- It does not maintain a repeating pattern and disrupts consistency.

Option 4: gjrjk

- Fills the blanks as: gr(gj)jk(rj)rj(kj)kg(rj)jj

- This has a potential repeat but does not create a consistent series in the given structure.

The correct answer is Option 2: jgjrk.