The majority of thyroid hormones are secreted as but small amounts of is also secreted from the follicle.

The correct answer is - T4, and T3.

Explanation:

The Thyroid glands are butterfly shape glands madeup of microscopic spherical structures known as thyroid follicles made up of cuboidal follicular cells. These cells produces the both major hormones of thyroid gland T4, and T3.

The majority of thyroid hormones are produced as T4 hormones approximately 80% but a small amount of 20% is released in the form of T3 hormones. However, the most active form of the thyroid hormone is T3 and to act on target cells, one iodine molecule have to be removed to convert T4 to T3.

it's c. (to reduce the greenhouse effect/carbon gasses)