Yup! The meaning changes slightly. 는 implies this paticular pizza, sort of like adding "unlike other X"

그 피자는 짜요 "That pizza, unlike the other pizzas, is salty".

그 피자가 짜요 "That pizza is salty"

But otherwise the subject partical 가 and the topic particle 는 have the same meaning

Yes, i tried both options and they were marked correct.