Given below are two statements. 
Statement I : Amino acids have property of ionisable nature of -NH₂ and –COOH groups, hence have different structures at different pH.  
Statement II : Amino acids can exist as zwitterionic form at acidic and basic pH.  
In the light of the above statements, choose the most appropriate answer from the options given below. 

SI: Amino acids are molecules that contain both an amino group (-NH2) and a carboxyl group (-COOH). These groups are ionisable, meaning they can gain or lose protons depending on the pH of the solution they are in. At different pH levels, amino acids can exist in different forms: as cations when the pH is low (acidic), as zwitter ions when the pH is near their isoelectric point (pH at which the net charge is zero) and as anions when the pH is high (basic). The ionisation state of these groups affects the overall charge and structure of the amino acid.
SII: Some amino acids can exist as zwitter ion in acidic pH and some can exist as zwitter ion in basic pH.