the numbers before chloro specify where the halo (chloro) is located at what Carbon, and the name tells you that the double bond is located on the C1=C2, unless another number came up after the chloro and before the propene, that would've told you where the double bond is located.
When it is not specified, it is understood that it is in the C1=C2 location
so, your answer is #1 (a)
if the chlorine is on the 2nd or 3rd Carbon, your C1 will be left with 2 Hydrogens, and the number one rule of E-Z is if one of the carbons in the double bond have 2 of the same substituent, you cannot have and E (opposite) or Z (same side)
and yes use E-Z, specially you have substituents connected to the C=C that are different, and not the usual carbon or hydrogen