We have to complete the questions based on the picture to the left, remembering to use the particle ‘が’ when answering a question.

We’re being asked who is reading a newspaper. Looking at the picture, we see that it is 佐藤さん（さとうさん）who is reading the newspaper. We answer as follows:
佐藤さんが新聞を読んでいます。
（さとうさんがしんぶんをよんでいます。）

We have to complete the questions based on the picture to the left, remembering to use the particle ‘が’ when answering a question.

We see that the answer provided is that 森さん（もりさん）is taking pictures. The question, then, is ‘Who is taking pictures?’ Note that, in the answer, the object is not repeated as it is already implied from the initial question. We answer as follows:
誰が写真を撮っていますか？
（だれがしゃしんをとっていますか？）

We have to complete the questions based on the picture to the left, remembering to use the particle ‘が’ when answering a question.

We’re being asked who is wearing glasses. Looking at the picture, we see that it is 山田さん. We answer as follows:
山田さんがめがねをかけています。

We have to complete the questions based on the picture to the left, remembering to use the particle ‘が’ when answering a question.

We see that the answer provided is that 田中さん（たなかさん）is wearing a hat. The question, then, is ‘Who is wearing a hat?’ Note that, in the answer, the object is not repeated as it is already implied from the initial question. We answer as follows:
誰が帽子を被っていますか？
（だれがぼうしをかぶっていますか？）