Which translator program reads small portions of a program at a time, translating them into machine instructions which are then executed immediately?

Interpreter is the correct answer for the above question.

Explanation:

The interpreter is a software program which is an example of a translator and it does not take whole code at a time for conversion. It converts the code on a line by line sequence. It takes some small code and then converts it into machine code. While the other translator takes the whole code at a time and converts it into machine code. The above question wants to ask about that technology which is used to convert some small code not the whole code at a time then the answer is an interpreter which is defined as above.