The scientist Konstantin Mereschkowsky knew in the early 1900s that plants make

The scientist Konstantin Mereschkowsky knew in the early 1900s that plants make their own food by using sunlight. He also saw tiny parts in plants called chloroplasts that do not appear in any animals. He hypothesized that chloroplasts are what help plants make food. After many more observations of all types of plants and animals, scientists are convinced today that chloroplasts make food for plants. Has the study of chloroplasts been scientific or pseudoscientific?

scientific, because a hypothesis and observations were made and then a conclusion was drawn
scientific, because scientists made a hypothesis and conclusion before making any observations
pseudoscience, because a hypothesis was believed to be true before any observations were made
pseudoscience, because beliefs in chloroplasts are based on subjective opinions