To express the relationship between the cost of the T-shirt and the cost of the socks mathematically, we start with the information given:
- A T-shirt costs 4 times as much as a pair of socks.
- A T-shirt costs $16.
This can be expressed as:
\[ 16 = 4s \]
Or rearranging this:
\[ 4s = 16 \]
So the correct mathematical sentence that expresses the information above is:
4s = 16.