**Explanation:**

The correct answer is option **B) bored**.

In this sentence, the speaker is describing their experience of watching a play. They found the play to be long and uninteresting. Based on this information, we can determine that the speaker's emotional state or reaction to the play was one of boredom.

Let's break down the options to understand why option B is the correct answer:

**a) tiring:**
- This option suggests that the play made the speaker feel tired.
- While it is possible for a long and uninteresting play to make someone feel tired, the sentence does not explicitly mention any physical fatigue.
- The main focus of the sentence is on the lack of interest in the play, not the physical exhaustion it may have caused.
- Therefore, this option is not the best choice to describe the speaker's emotional state.

**b) bored:**
- This option suggests that the play did not engage the speaker's interest, resulting in a feeling of boredom.
- The sentence clearly states that the play was "long and uninteresting."
- These qualities are likely to make someone feel bored.
- Therefore, this option is the most suitable choice to describe the speaker's emotional state.

**c) boring:**
- This option suggests that the play itself was uninteresting.
- While it is true that the sentence mentions the play being uninteresting, it is not the play that is described as boring.
- Instead, the speaker's emotional state is the focus, and they felt bored while watching the play.
- Therefore, this option is not the best choice to describe the speaker's emotional state.

In conclusion, the correct answer is option **B) bored** because it accurately describes the speaker's emotional state of feeling uninterested and unengaged while watching the long and uninteresting play.