How did the earliest chordates obtain food?
a. They were filter-feeders
b. They were herbivores, consuming photosynthetic algae.
c. They had symbiotic green algae that produced most of their energy.
d. They were predators, catching mostly marine crustaceans.
e. They were decomposers, consuming dead worms and crustaceans.

Option A.

They were filter feeders.

Explanation:

The first chordates appear in the Cambrian period and the fossil record shows it to be around 530 milion years ago. This chordates was found in China and recorded in 1995.

The earliest chordates obtain food by filter feeding. They taking in water through the mouth and filter the feed through gills silts.

Chordates characteristics are;

They have notochord.

They have hollow nerve

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.

thats not even an aswer choice