To find the ratio illustrating how many heads of lettuce, \( x \), Timothy would need to feed 275 guests, we can start from the ratio given for 100 guests.
The relationship between the number of heads of lettuce and the number of guests can be expressed as:
\[ \frac{37}{100} = \frac{x}{275} \]
This means for every 37 heads of lettuce, there are 100 guests, and we want to find \( x \) heads of lettuce for 275 guests.
Thus, the correct ratio is:
\[ \frac{37}{100} = \frac{x}{275} \]
So, the answer is:
37/100 = x/275