Which of the following was the leading cause of global fossil carbon emissions in 2004?
a. petroleum
b. coal
c. natural gas
d. cement production

The correct answer is option A, Petroleum

Explanation:

In 2004, the majority contribution is pollution was due to the enhanced use of petroleum and fossil fuels because of the  rapid industrial growth & production along with enhanced vehicle ownership. A per an estimate in 2004, U.S. has nearly 314 million metric tons of carbon-equivalent released from  cars and light trucks which is equivalent to coal train 50,000 miles long.

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products