Answer:
Electromagnetic force
Step-by-step explanation:
The attraction forces that causes the compression of the atom leading the to decrease in Atomic Radius is "Electromagnetic force".
Electrons (negatively charged) are strongly bonded with the nucleus (positive nucleus) by electromagnetic force. Electromagnetic force allows the electrosn to move in a specific orbit around the nucleus.
Atomic radius decreases from left to right in a periodic table because when valence electrosn are added at the same time the number of protons in nucleus increases. This increases the nuclear charge that attracts the electrons more strongly towards the nucleus and decreases the atomic radius.
Hence, the correct answer is "electromagnetic force".