Which of the following statements are CORRECT with respect to cardiac activity?
A. Nervous control of cardiac activity is brought about by Autonomous nervous system (ANS).
B. ANS receives inputs from proprio-receptors, chemoreceptors and baroreceptors for nervous control of heart beat.
C. Cardiac activity increases with elevated blood levels of $\text{K}^+$ and $\text{Na}^+$.
D. Conditions like hypoxia, acidosis cause increase in cardiac activity.

Nervous control of cardiac activity is regulated by the cardiovascular center in the medulla oblongata through the autonomic nervous system (ANS).

The cardiovascular center receives inputs from sensory receptors such as proprioceptors, chemoreceptors, and baroreceptors to regulate the heart beat.

Elevated blood levels of $\text{K}^+$ and $\text{Na}^+$ decrease heart rate and contractility. Excess $\text{Na}^+$ blocks $\text{Ca}^{2+}$ inflow during cardiac action potential, decreasing the force of contraction, while excess $\text{K}^+$ blocks the generation of action potentials.

Conditions like hypoxia (low oxygen), acidosis (low pH), and alkalosis (high pH) depress cardiac activity.

Thus, statements A and B are correct, while C and D are incorrect.

Answer: A and B only.