Final answer:
The correct function for the price of a pizza with toppings is p(t) = 6.45 + 0.90t, where each topping added increases the total price by $0.90.
Step-by-step explanation:
The function that represents the situation where the price p of a pizza is $6.45 plus $0.90 for each of the t toppings on the pizza is: p(t) = 6.45 + 0.90t. This is because the base price of the pizza is $6.45, which is a fixed cost, and each topping adds an additional variable cost of $0.90 per topping. So, for every topping added (t), the total price increases by $0.90.