If an object repels from another negatively charged object, the first object is

The first object must be negatively charged.

Explanation:

There are two types of charged particles: Positively charged and negatively charged.

Positively charged particles carry a positive charge negatively charged particles carry a negative charge.

We know that:

Like charges repel each other and unlike charges attract each other. This means that positive charge will be repelled by positive charge and it will be attracted by a negative charge.

In the question, an object is being repelled by another object which is negatively charged. Thus, the first object must carry the same charge as the other object.

Hence, the first object must be negatively charged.

d) the number of neutrons plus the number of protons