The cost for an upcoming field trip is $30 per student. The cost of the field trip, in dollars, is a function of the number of students.

The function \( C(x) = 30x \) represents the total cost of the field trip in dollars, where \( x \) is the number of students. Since the cost per student is \( 30 \) dollars, the outputs will depend on the number of students.

If we check the possible outputs based on the values given:

1. For \( x = 1 \): \( C(1) = 30 \times 1 = 30 \)
2. For \( x = 2 \): \( C(2) = 30 \times 2 = 60 \)
3. For \( x = 3 \): \( C(3) = 30 \times 3 = 90 \)
4. For \( x = 4 \): \( C(4) = 30 \times 4 = 120 \)
5. For \( x = 5 \): \( C(5) = 30 \times 5 = 150 \)

The outputs (possible costs) based on \( x \) must be multiples of \( 30 \).

Now analyzing the specific options provided:

• 100: Not possible
• 30: Possible (when \( x = 1 \))
• 20: Not possible
• 50: Not possible
• 90: Possible (when \( x = 3 \))

Thus, the possible outputs (range) for the function \( C(x) = 30x \) given the provided options are:

• 30
• 90

These are the only correct responses based on the function defined.