Correct Answer: Systematic

Solution : The correct choice is the fourth option.

Sporadic means something that is happening not regularly or is non-continuous. Systematic means something that is done with a fixed plan methodically, which makes it the opposite of "sporadic".

The meanings of the other options are as follows:

• Scattered means disorganised.
• Random means lacking a definite plan.
• Rare means an event that does not occur very often.