Answer: Interrogative
Explanation: Mood of a sentence is used to express the intention of the auhtor (speaker or writer). The mood can be of 4 types:
- Indicative, when express facts;
- Interrogative, when refers to a question;
- Conditional, is used when situations are uncertain or depends on something else;
- Imperative, when it's being ask or order someone to do something;
The sentence "Will you pick up the dog's toys in the yeard, please?" is an Interrogative, because it is asking a question and, grammatically, the formation of the phrase is: auxiliary verb + another verb.