In an experiment performed in a space station, a force of 60 n causes an object to have an acceleration equal to 4m/s. what is the object's mass?

I'm afraid you're not paying attention.  This question is loaded with
all the important words, and you don't recognize Newton's second
law of motion.  Didn't you notice the  "force", "acceleration", and
"mass" all over the place in there ?

Newton's 2nd law:      Force = (mass) x (acceleration)

The answer is going to be 'mass', so let's divide
each side of Newton's law by 'acceleration':

                                   Mass = (force) / (acceleration)

Now, just write in the numbers that the question gave you:

                  force =  60 newtons
       acceleration =  4 m/s²

Here's the equation again:     Mass = (force) / (acceleration)      

                                                       = (60 N) / (4 m/s²)

                                                       =  15 kg .  

Iwould say a is accurate