Explanation:

- Let's break down the series: 136, 137, 135, 138, 134, 139...

- Notice alternating patterns:

- One pattern increases by 1: 136, 137, 138, 139...

- The other pattern decreases by 1: 135, 134...

- Based on these patterns, the next decreasing number after 134 is 133.

- Option 1: 133: This matches the pattern of decreasing by 1.

- Option 2: 136: Doesn't fit the expected sequence.

- Option 3: 139: Already in the sequence as an increasing number.

- Option 4: 138: Also doesn't fit the next expected number.

- So, the correct answer is: Option 1: 133