Answer:
Option A and option C are the correct option,
Step-by-step explanation:
A. Green algae are autotrophs like plants and produce their own food by photosynthesis. They also have chloroplasts for photosynthesis. In this food web they are bottom of the the web that suggests too that green algae is the producer.
C. Mangroves are the group of plants found in the intertidal coastal area. Mangroves also make their own food by the process of photosynthesis.