Which is biotic?
a. wind
b. iron gate
c. sunlight
d. dead leaf

D

Explanation:

Although the leaf in option D is dead, a leaf is still considered biotic.

If an organism is dead, that just means that the organism was living, at one point.

Any organism that can display the characteristics required of life, can be considered biotic.

Abiotic substances are things such as minerals (iron gate), wind, sunlight, vitamins, etc.

These substances were never living, they may have been part of a living organism, but as separate entities, they do not have the characteristics required for life

b. heterotroph

explanation:

it cools slower in the earth meaning the crystals have more time to form than lava on the surface