To determine how many times the number of bacteria in the human body is greater than the number of genes, we can divide the number of bacteria by the number of genes.
- The number of bacteria in the human body is given as \( 1 \times 10^{12} \).
- The number of genes in the human body is given as \( 4 \times 10^4 \).
Now, performing the division:
\[ \frac{1 \times 10^{12}}{4 \times 10^4} \]
This simplifies to:
\[ \frac{1}{4} \times \frac{10^{12}}{10^4} = \frac{1}{4} \times 10^{12 - 4} = \frac{1}{4} \times 10^8 = 0.25 \times 10^8 = 2.5 \times 10^7 \]
Converting \( 2.5 \times 10^7 \) to a standard number:
\[ 2.5 \times 10^7 = 25,000,000 \]
So, the number of bacteria is 25,000,000 times greater than the number of genes.
The answer is:
C: 25,000,000