This is a simple subtraction series,

Correct Option: D

This is a simple subtraction series, in which 4 is subtracted from each number to arrive at the next.

This simple addition series adds 4 to each number to arrive at the next.

Correct Option: E

This simple addition series adds 4 to each number to arrive at the next.

This is a simple subtraction series,

Correct Option: E

This is a simple subtraction series, in which 3 is subtracted from each number to arrive at the next.

This is an alternating addition series with a random number, 4, interpolated as every third number.

Correct Option: D

This is an alternating addition series with a random number, 4, interpolated as every third number. In the main series, 1 is added, then 2 is added, then 1, then 2, and so on.

This is an alternating repetition series, in which a random number, 61, is interpolated as every third number into an otherwise simple subtraction series.

Correct Option: E

This is an alternating repetition series, in which a random number, 61, is interpolated as every third number into an otherwise simple subtraction series. Starting with the second number, 57, each number (except 61) is 7 less than the previous number.